In 2017, the 84th best pitcher averaged approximately 10 runs prevented, establishing the 90th percentile performance point; in 2018, the 89th best pitcher averaged approximately 10 runs prevented, suggesting that the 90th percentile performance did not change. If you like false certainty, even here the decimal points look similar, as the 2018 cut-off was 10.221 average runs prevented versus 10.229 average runs prevented in 2017. Let’s call it 10 Average Runs Prevented for fun…

 Exploring Runs Prevented || Aces Do Not Exist || Rotation Spots || Third-Time Charmers

What is Runs Prevented? Runs Prevented is a relatively basic statistic that attempts to measure the quality of a pitcher’s performance within their run environment (which is roughly the combination of their ballpark, which can impact scoring, and their league, which can impact the mix of talent faced). Measuring pitching is difficult because unlike batting stats, you cannot simply “count up” with pitchers; a team that scores 750 runs is  likely better than a team that scores 700 runs, but a team that allows 650 runs is likely better than a team that allows 700 runs. So, assessing pitching in a “run environment” requires accounting for that “negative space” (in this example, between 650 RA and 700 RA). Throughout the 2018 season, I developed an Average Runs Prevented statistic that attempted to track variance in park factors (between Baseball Prospectus Pitching Park Factor and Baseball Reference Park Factors) as well as variance in league environments. Usually these differences did not amount to much, but tracking them is an important step to understanding variance and reflecting uncertainty in the Runs Prevented metric: I can say “Jeremy Jeffress prevented 24.63337 runs in 2018,” or I can say “on average Jeremy Jeffress prevented between 23 and 26 runs in 2018,” or I can say, “Jeffress prevented 25 runs.”

…The short lesson: if you’re an MLB pitcher that prevented 10 runs, you’re really, really good. This holds regardless of role. In 2018, the top ten percent of all MLB pitchers featured 53 starting pitchers and 36 relief pitchers, which is quite a swing in favor of starting pitching quality; in 2017, these 90th percentile pitchers featured 41 relievers and 43 starters. What’s important here is to takeaway that great relievers prevent enough runs to break into the top threshold of league performance; Runs Prevention need not categorically be dominated by starting pitching, which is one reason the Brewers did not need a starting pitcher at the trade deadline (thanks to their strong bullpen).

Aces are more difficult to define than “Average Runs Prevented.” I can at least give you a math equation for Average Runs Prevented at the end of the day. But an “ace” can be many things;

• Some fans want an ace to be a breathy “dude” or “guy”, a “stud” atop the rotation. File this one under the debate about playoff dudes,  “Do you want Jhoulys Chacin and Wade Miley to pitch in the playoffs?” (Yes, actually);

• Some people ascribe to a theory than an “ace” is simply the best pitcher on each MLB team (e.g., 30 teams means 30 aces, and no team can have more than one ace);

• Scouts like to define “aces” in very rigorous ways, focusing on the quality of a pitcher’s stuff (typically better than average fastball and off-speed or breaking ball is the minimum stuff requirement for acehood), as well as their command (must be great), and probably their frame, too (it’s good to project innings from an ace). But I take it that this is not how most fans mean “ace,” and it’s also no fun because aces rarely exist under this mold (#EveryoneIsAMidRotationStarter);

• Finally, there’s the simple stipulation that an “ace” is an elite starting pitcher, at the top of the league in terms of performance (presumably, hopefully, for multiple consecutive years. For example, this is why people say Clayton Kershaw is an ace, but Junior Guerra is not. I used to be sure of the importance of consistency, but….well, aces hardly exist under this requirement, either).

In this analysis, I am going to demonstrate two of the shortcomings with the idea of using performance to define the concept of an ace.

(1) Threshold of Greatness. Seeking the 90th percentile of MLB pitchers seems like a very high standard; it’s quite literally the top of the league, but includes a large enough group of pitchers to make meaningful comparisons. What I mean by this is, if we used a more strict threshold, there really would not be any aces; take the Top 10 pitchers by Runs Prevented in 2017 and 2018, for instance:

I rather like this, in the sense that it demonstrates that aces do not exist, but it doesn’t pass the eye test. If you’ve designed a threshold where only Corey Kluber, Chris Sale, and Max Scherzer are aces in 2017 and 2018, but not Kyle Freeland, Justin Verlander, Clayton Kershaw, Blake Snell, or Jacob deGrom, you’ve probably missed the threshold and poorly defined the concept.

An interesting problem arises with using the 90th percentile threshold, however: starting pitchers no longer dominate the proceedings, and 10 Average Runs Prevented is the measure for an ace. This surely won’t do for Brewers fans, for example, as 2016 Junior Guerra is absolutely, positively an ace under this regard; interestingly enough, so are 2018 Jeremy Jeffress, Josh Hader, and Wade Miley. Of course, this is conceptually interesting because Brewers fans absolutely did not want Miley to work in the rotation, and he was an “ace,” it turns out. Really, a truly fantastic pitcher, better than 90 percent of the MLB. Jeffress and Hader are difficult in terms of “acehood” because they do not start ballgames; but it’s not clear to me than an ace must start ballgames.

Consider the false controversy to open 2018, regarding whether or not Josh Hader should start or work in his relief role; as a starter, the concern is clearly that Hader does not have the command or pitching profile to work through a batting order multiple times, and based on news throughout the season, his delivery is probably too high effort to withstand a starting workload. But that was never the debate; the debate among angry fans was, “Josh Hader should start because the Brewers must see whether he can be an ace.” Ironically, based on the 90th percentile threshold of Runs Prevented, Hader is an ace, undoubtedly so (in fact, he’s better than 95 percent of the league in 2018; Jeffress was even better, beating 98 percent of the MLB). In this debate, it seems that the ideal of “finding an ace by making sure they can start games” misses the concept of what an ace ought to do (“consistently prevent runs at an elite level”), and so the Hader starting pitching controversy falls by the wayside.

Both Hader and Jeffress are aces, on this model. As they should be.

(2) Consistency. Josh Hader showed flashes of brilliance during the 2017 season, in which he established a clearly valuable MLB “floor” performance level, and raised debates about how high the “ceiling” performance could be. I gather this is in part why fans wanted so badly to see Hader start; when he began his career in the bullpen, it was certainly due to his tough season at Triple-A Colorado Springs, where he lost his breaking ball and had his stuff and command profile back-up a little bit. Yet Hader excelled in his MLB debut role, working through some command issues by offsetting bad outings with a dozen scoreless multi-inning appearances. Hader prevented between 13 and 14 runs in 47 and 2/3 innings.

Any team will receive considerable value from a pitcher that prevents more than 10 runs in a season; no team would balk at a chance at 90th percentile runs prevention production. Yet, there is more value to be had from pitchers that can repeat the feat in consecutive seasons. For example, 639 pitchers worked in both 2017 and 2018 seasons, with considerable variance in their production. The typical back-to-back pitcher in 2017 and 2018 found their runs prevented total shift by at least nine runs, with their innings pitched total fluctuating by 33. If you ascribe to the rule of thumb that approximately ten runs are equivalent to “one win” when balancing Runs Scored and Runs Allowed, the MLB pitchers that worked in 2017 and 2018 fluctuated enough to produce as many as 575 total wins (or losses), depending on how teams balanced their resources (as a side note, this is one reason organizations should not ever tank, and should always try to compete: there are always tons of runs that can be “captured” every year through trades, free agency, and player development fluctuations).

This is where I believe fans and analysts turn against “one year aces” like Junior Guerra. The idea is not that Guerra was not valuable to the Brewers in 2016, but that it is more valuable to have a pitcher that a team can “depend” on to produce 90th percentile performance year-in, and year-out. The trouble is, these pitchers do not readily exist. Looking at 2017 and 2018, here are the pitchers that were able to produce 10 Average Runs Prevented (or better) in both seasons:

This seems like a good list, for two reasons: (1) it’s intuitive enough to pass the “eye test” in terms of including pitchers like deGrom and Kershaw, but it also includes some “newcomer” aces like Aaron Nola; (2) it includes enough counterintuitive pitchers that we can look into new cases and further define quality pitching roles. Here, I’m thinking of Josh Hader (who is an ace in relief), JA Happ (who has morphed into an extremely consistent late career pitcher), and Dellin Betances (who is typically criticized as a middle reliever when it comes to contract negotiation matters, but should be thought of in the highest terms of consistency). Moreover, this table shows the benefit of being more inclusive in terms of defining aces, rather than less exclusive. Here’s what happens if you only consider pitchers with consecutive 20+ Runs Prevented seasons to be aces:

This list is visually appealing insofar as we all know that these pitchers are great, the top of the game in fact. This group would be the true 99th percentile of the game of baseball at the moment. But, it does not capture easily acquired pitchers (except for the Cleveland arms, perhaps, in Carlos Carrasco and Corey Kluber, this is an expensive group in terms of draft status, contract, or prospect resources required for acquisition). So, the cases of aces exclude most MLB teams from acquiring aces. Furthermore, there is no diversity of roles in this table, and to my eye that seems like the biggest shortcoming in this definition of the ace: for if we continue to define aces according to the highest possible standard, we will continue to replay and repeat the “Josh Hader should start” debate, and miss the reasons why Wade Miley or Jeremy Jeffress could be aces, too.

Building a pitching staff based around flexible roles, or based on elite relief roles and interchangeable starting rotation roles, does not preclude acehood. In fact, the 2018 Brewers demonstrate that effectively, both with multi-year consistent aces (Hader) and (potentially) one-off successes (Jeffress, Miley).

New Runs Prevented Workbook || Runs Prevented Primer

https://docs.google.com/spreadsheets/d/1KBQ19VcMZ4g7oW1jkGiYwxCadqjw3rYXkqN200f4lHc/edit?usp=sharing

This is not even some “to-be-expected” regression, as even if one wishes to look at Deserved Runs Average (DRA) throughout the season as a “true” measure of the Brewers talent (which should be cautioned), the Brewers would have been expected to allow anywhere between 23 and 30 fewer second half runs than they actually have allowed.

This is unforeseen and catastrophic.

The blame can be spread around to everyone, from the post-forearm injury Junior Guerra (10 IP, 9 runs on July 24 & 29), injured reliever Matt Albers (1.7 IP, 10 R), former? closer Corey Knebel (9.3 IP, 8 R entering Sunday), and even rookie rotation depth Freddy Peralta (19 IP, 17 R since the break). Worse yet, there is a sense of adding insult to injury, as newly acquired Joakim Soria hit the disabled list promptly after surrendering a grand slam home run in a devastating loss to San Diego, and quietly effective Taylor Williams hit the disabled list with an elbow injury. While fans will feel less sympathy for Matt Albers, who had a couple of different bouts of ineffectiveness surrounded by separate disabled list stints, the veteran righty was crucial to early season success (25 IP, 4 R through the end of May) and each day his injury status and effectiveness is not answered is a day that manager Craig Counsell must carefully ration Jeremy Jeffress and Josh Hader with little back-up. The same goes for Williams, and now Soria; while Jacob Barnes was previously an impact reliever and boasts solid peripherals and a 2.99 Deserved Run Average (DRA), his runs prevention performance in 2018 has not been to the level of that injured trio, and now it’s Barnes, Corbin Burnes, and Jordan Lyles trying to nail down the quietly effective support roles.

It’s as simple as this: the Brewers’ bullpen has two truly fantastic options in Jeffress and Hader, and those options will be great regardless of their surrounding cast. For the purposes of contending, however, this duo is amplified when Stearns’s excellent depth picks (Albers, Williams, even Corbin Burnes), closer (Knebel), and additional acquisitions (Soria) are performing well. Jeffress and Hader cannot do it themselves.

Injuries have also trimmed the rotation, as Brent Suter’s torn elbow ligament and Zach Davies’s back ailments have limited the Brewers’ effective rotational depth. Using Baseball Reference Three Year Park factors, both Suter and Davies combined for 18 Runs Prevented over 273 innings in 2017, offering excellent middle and replacement rotation depth. That level of impact depth performance will not be matched by the duo in 2018. Additionally, even if one could have argued that the club might not have expected Jimmy Nelson to return from his shoulder injury in 2018, having that materialize as a likely injury-scenario reality in 2018 is quite another ballgame. Consider this as Freddy Peralta meets a likely innings limit, Chase Anderson continues an uneven season, and Brandon Woodruff finds himself without a rotational role: #TeamDepth is now basically #TeamNecessity in terms of rotation building.

There’s no need to state it any other way: as much as one would like to criticize the Brewers pitching staff, and GM David Stearns for his failure to build a staff, the club is now to the point where injuries are diminishing even his strongest moves. The Soria trade looms loudest here, as the Brewers grabbed a legitimate high leverage, veteran reliever at the trade deadline and did not get six innings from his right arm before he hit the DL with a groin injury; Albers and Williams could be fan whipping posts when they were ineffective, but the Albers free agency deal looked like a brilliant low-cost gamble early in the season while Williams seemed poised to catapult himself into the high leverage workload discussion (Williams worked a 17.3 IP, 5 R stretch, Holding three leads, from June until the All Star Break).

Citing injuries to the pitching staff is not an “excuse” for the poor performance.

It would have been enough to deal with this group of recent injuries and setbacks, but the Brewers also simultaneously were gifted with a set of role reversions on the pitching staff. Corey Knebel’s descent from excellent closer in 2017 cost the Brewers a chance at a truly elite relief corps; according to Baseball Reference Three Year Park Factors, Knebel prevented nearly 25 runs in 2017. Even a 50 percent regression from that performance level would fit nicely with Jeffress and Hader, who have both been consistent Top 25 pitchers in the 2018 MLB. Add in the aforementioned struggles of Peralta, Barnes, and a bit of stalled usage from the shuttled Houser (he’s only worked two MLB appearances from July onward), and Counsell’s strategic options are looking much more thin while they are also being exasperated by some ineffective starts.

Beyond these role question marks, it is worth questioning the timing of the inclusion of Jorge Lopez in the Mike Moustakas trade. Since Lopez has served the season as an up-and-down member of the Triple-A / MLB “shuttle team” relief squad, discussions of the quality of Lopez’s performance were largely nonexistent at the trade deadline (I’m also guilty of this charge). But, it is worth emphasizing that as a back-roster depth strategy, the “shuttle team” prevented runs at a solid clip, especially when one considers the nature of this replacement role and the likely quality of other replacement pitchers to be acquired in their place.

In fact, these shuttle relievers combined to produce near-average aggregate performance for the Brewers, which leads one to question why Stearns traded Lopez and simultaneously decided to keep Brandon Woodruff at the Triple-A level to serve as replacement starting pitching depth. With Lopez in the Royals system and Woodruff now serving as starting pitching depth, the revolving door relief strategy is effectively dead at what could be the worst time of the season. Given that Woodruff boats a 3.55 DRA at the MLB level to accompany a 52 percent ground ball rate, while also demonstrating an average DRA at Colorado Springs with a consistent ground ball rate there, it is worth questioning why Stearns has not simply replaced Peralta with Woodruff (on the one hand) or simply promoted Woodruff to a steady MLB relief role (on the other hand). According to Brooks Baseball, the relief role is agreeing with Woodruff, who is throwing a sizzling 95-to-96 MPH fastball with more armside run than his 2017 variation, complete with steady change up and slider usage (both with more whiffs than in 2017, too).

This is not a bottomless pit (yet). That the Brewers remain the 12th best pitching staff in the MLB, within one standard deviation of the 10th spot, and sixth best pitching staff in the National League, should demonstrate just how good the club has been for most of the year. Indeed, this pitching staff has fallen off, and it’s important to underscore that it’s not simply “regression,” but a bad combination of regression, injuries, and strategic missteps at the worst possible time. But there could be a quick way out of this issue for the club:

• Get Zach Davies healthy, without any further setbacks, and use him to replace Freddy Peralta in the rotation.

• Develop an MLB role for Brandon Woodruff; preferably this would be a rotational role to spell another ineffective starter down the stretch (or add a sixth man for September), but even a well-defined one-inning bullpen role could be extremely helpful at the moment.

• Re-evaluate depth roles for Ariel Hernandez, Jordan Lyles, Alec Asher, and Aaron Wilkerson, and make any necessary waiver trades to boost the pitching staff. E.g., is Jordan Lyles the right arm to work in the shadow of the successful Triple-A shuttle crew? Is now the best time to make a potential long-term development play for Ariel Hernandez?

• Reconsider Adrian Houser’s shuttle role in favor of a regular one-inning role.

With the assumption that some combination of Soria, Albers, and Williams can get healthy for the stretch run, and that some of the “role regression” pitchers can make adjustments at the MLB level once again, this is a pitching staff that can improve quickly and regain its flexible frontier of roles and runs prevention that were celebrated in April and May. With Zach Davies healthy, a waiver trade acquisition (or two), and potentially prominent roles for two righties that can rush it up there (Woodruff and Houser), this pitching staff can rebound. Now we wait and watch.

Last night in Pittsburgh, Jeffress worked four outs. During the outing, the righty allowed one of two inherited runners to score, and also allowed one run of his own to cross the plate. Otherwise, he also struck out three batters, and thanks to a Brewers offense that scored some runs, Jeffress easily worked within his margin of error to help convert his twelfth lead of the season into a win (Jeffress has three saves and nine holds; last night was his ninth hold). But it is worth emphasizing that for any perception that Jeffress is in the midst of a rough stretch (five of six inherited runners scored in June), the righty is still maintaining the strengths of his profile. For example, Jeffress has allowed three groundballs for every two flyballs, while also striking out 35 percent of batters faced; it’s no wonder that the relief ace has allowed only one run of his own over this stretch.

All of this is a brief analysis of appreciation for one of the very best relievers in baseball, the member of yet another iconic Brewers bullpen duo (the previous being with southpaw Will Smith). Jeffress’s recent stretch demonstrates that even though one could perceive that the strong bullpen is “regressing,” by point of fact the underlying performance remains strong and the bullpen, if anything, has faltered from “phenomenal” to “merely great.”

Photo Credit: Charles LeClaire, USA Today Sports Images