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).

Related:
Depth Beats Attrition
Trust the Rotation
Aces Do Not Exist
How to Turn One Hader into Two and a Half Chris Sales

Teams are eager to rely on their bullpens more frequently, and at 5.18 IP/GS for his starters, manager Craig Counsell is about as eager as anyone to turn away from the third time through the order as a starter.

If you’re new to baseball analytics, one of the best possible strategies to learn is the starting pitcher’s “times facing a batting order.” The table above demonstrates On-Base-Percentage plus Slugging-Percentage each time through the order for National League starting pitchers. This may seem like a trivial aspect of the game, but if you read the new midseason scouting reports emerging on your favorite arms, or even look into 2018 MLB Draft scouting reports, chances are you’ll see a line like “without a third pitch, a role in the bullpen could be most likely.” What you’re reading, in nearly any variation of this line, is the strategic idea that in order to beat MLB batters a third time through the order, a starting pitcher is going to need additional pitches to cross-up batters and make adjustments as the game deepens. Milwaukee left-hander Warren Spahn is classically attributed with the quote, “pitchers need two pitches, one they’re looking for and one to cross them up,” but even here Spahn was not quite right; a pitcher needs as many pitches as are necessary to adjust to their designated role. I imagine that if you’re Warren Spahn (perhaps much like Ben Sheets or Clayton Kershaw), life is rather easy with mostly two pitches; if you’re Dave Bush or Victor Santos or Zach Davies or pretty much anyone of the other 300+ starters that work in the MLB, life with only two pitches would probably be miserable.

But perhaps the stats speak on their own: last year, the average NL batter the first time through the order was Cory Spangenberg. By the third time through the order, the average NL batter was Christian Yelich. In order to keep batters closer to the Cory Spangenberg level of production, having command of that third pitch (with a quality “stuff” grade, too) will get the scouts ready to slap that “#3 SP” Overall Future Potential grade.

Manager Craig Counsell was handed a group of supposedly below average-to-horrendous starting pitchers according to most Brewers fans, but as most fans could have surmised from the 2017 squad, pitching was the strength of the organization. And indeed, pitching has continued to serve as the strength of the 2018 club, although statistics like Deserved Run Average suggest that the club may be due for some regression to the mean (in terms of preventing runs). But what was most important about the 2017-2018 offseason was that GM David Stearns built a pitching system, and Counsell’s eagerness to pull starters at just the right time has indeed reflected a machine-oriented approach to pitching. Setting aside the injured Zach Davies and the mechanics-ironing Chase Anderson, the 2018 Brewers starting rotation is lead by Chacin (4 Runs Prevented in 69.0 IP), Brent Suter (2 Runs Prevented in 63.3 IP), and Junior Guerra (approximately 9 Runs Prevented in 60.3 IP after Tuesday night). Counsell has pulled these pitchers early almost uniformly; the Table below compares each pitcher’s last major workload as a starting pitcher to their 2018 workload, in terms of facing a batting order multiple times:

This is what managing with an elite bullpen can do for someone: pretty much every night of the week, Counsell can give each starting pitcher the same workload. In contrast to the narrative of burned out bullpens, which Kyle Lesniewski has also studied at Brew Crew Ball, it is worth arguing that Counsell is providing starting pitchers with a clearer definition of a workload. In fact, the old saying for starting pitchers to “go as deep as you can into the game” is rather problematic; if your stuff isn’t there, you’re probably done after 100 pitches and five (or fewer innings), which will be offset by the great 7.0-to-8.0 IP evenings, or complete games. Counsell and the Brewers are almost giving their starting pitchers better role certainty than any “traditional” starting pitcher has ever had (at least in the last 30 years): “give me your best 16 outs.” This is how you turn Guerra, Chacin, and Suter in a 15 Runs Prevented machine, which is one hell of a low rotation, by the way, and exactly the type of performance that turns a low rotation into an entity that offsets the lack of a so-called “Ace” at the top.

Has it worked? The Table below demonstrates that while there are some hiccups along the way, this Big Three low rotation has indeed improved in at least one area of the game, and in some cases the third time through the batting order is receiving grand benefits. These stats are even before Guerra’s course correction at Cleveland:

What is notable about minimizing a pitcher’s times through the batting order is that they can theoretically readjust their plan of attack. Someone like Guerra or Chacin no longer has to think about establishing his best stuff and figuring out what he’s going to do 100 pitches later; Suter might not ever have been expected to go that deep into ballgames, but even the Raptor-esque southpaw can arguably find some benefit in his ballgame by understanding that he needs to go 16 outs. Looking through Brooks Baseball pitching logs, it is arguably the case that what Counsell (and presumably Stearns, coaching staff, and the Front Office in this case) is doing is indeed turning each of these guys into….let’s call them “really, really long relievers who start the game”:

• According to Brooks Baseball, compared to his full season in 2016, Junior Guerra cut his splitter and slider usage (both below 15 percent!) while increasing his secondary running fastball (which Guerra selected approximately 23 percent of the time entering Tuesday night). As a result, Guerra is getting more whiffs on both of his fastballs as a group, and improving his slider whiffs without yielding too much value from his splitter. He’s also improving his pop-ups, suggesting batters are getting weak contact even though they are facing his fastball more frequently (presumably making Guerra more “predictable”).

• As covered by Andrew Salzman in the latest Weekend Recap at BPMilwaukee, Brent Suter is becoming a fastballl-first pitcher. The southpaw is firing what appears to be a near-cutting, rising fastball (think Jacob Barnes) two-thirds of his offerings, with good results in terms of improving swings-and-misses.

• By contrast, Chacin is much more of his previous self, with the caveat that he’s working his slider slightly more frequently than in 2017 while moving away from his primary fastball a bit. His outcomes with these pitches are rather similar as well, which suggests that even if the Brewers are deploying Chacin in a manner that is more systematic and potentially more radical, he is not deviating from what got him through a very successful 2017 campaign, earning him his excellent contract.

Milwaukee is receiving much deserved praise for their bullpen, which was expertly curated by David Stearns during his first two seasons with the club. Now the rewards are visible during what could become one of the most important seasons in franchise history, returning the club to their first extending contending window in quite some time. But it is worth emphasizing that Stearns was correct in assembling a starting pitching staff that could complement the relief staff, and together with the efficient fielders, the arms are a Runs Prevented machine. None of these moves were terribly difficult to make, either, which means that the most thrilling part of this series of moves is that they can be repeated in future seasons: Junior Guerra was Stearns’s very first acquisition, Brent Suter was a deep draft pick during the Doug Melvin era that was freed into a stunning big league role, and Jhoulys Chacin was a proven veteran signed off the margins of an underwhelming free agency class that nevertheless yielded some surprising contracts elsewhere. This is what systematic baseball can look like in Milwaukee, and it involves neither being “cheap” (Chacin signed a decent guaranteed deal) nor “dogmatic” about acquisition style (waivers, free agency, and draft are represented here). Most importantly for the prospect arms, both hyped (Corbin Burnes and Luis Ortiz) and unassuming (Freddy Peralta and others), the Brewers front office is gleefully demonstrated that nobody needs aces any longer. Bring your two best pitches for 16 outs, and let’s get on with it!

Photo Credit: David Richard, USA Today Sports Images

Resources:
Baseball Reference. Player Pitching Splits, NL Pitching Splits, 2016-2018 [CSV].