Runs Prevented Rankings I

Over the last couple of months, some comments based on Runs Prevented have helped me to re-evaluate how I present the statistic on the website (and, by extension, on BPMilwaukee Twitter, where I publish the Brewers Daily Pythagorean (or Run Differential, RS / RA) record). Thus, in March I posted a basic explanation of how I use Runs Prevented. Now, I’d like to actually publish periodic rankings of MLB team performance by Runs Prevented.

Explanation: Exploring Runs Prevented

Following a new format for my articles (where possible), the tables will be presented first for those who do not wish to read about the guts.

Table One: 2018 Runs Prevented by MLB, AL / NL, cFIP, and DRA; Ranked by Current AL / NL Runs Prevented

If you cite this table, please link this article and cite Baseball Prospectus and Baseball Reference.

At the team level, Runs Prevented basically expresses the extent to which a club’s pitching staff is better or worse than the league average adjusted for their park factor. Thus, it scales team pitching production to the environment faced by pitchers (both in terms of overall league, and in terms of park). Yet, this is only one way to present the stat; strength of schedule could be included, and different park factors could also be used. I happen to prefer the multi-year factor published on Baseball Reference, but that’s not to say that other metrics are not valid for other presentations of this statistic.

Table Two: DRA Correction of 2018 Runs Prevented for 162 Game Performance

If you cite this table, please link this article and cite Baseball Prospectus and Baseball Reference.

To account for these types of variances, in recent years I have periodically scaled Runs Prevented to Deserved Run Average (DRA) and contextual Fielding Independent Pitching (cFIP) stats. The table above demonstrates 162-game Runs Allowed and “DRA Allowed,” along with an estimate using DRA to correct Runs Prevented. The benefit of using these stats to publish Runs Prevented metrics is that one can attempt to use two predictive metrics to assess teamwide performance. This essentially could help to scale expectations about whether a club’s Runs Prevented performance is sustainable; for example, as Table One showed, the Brewers’ exceptional pitching staff, a top five team by runs prevented, is basically on pace to be an average club over 162 games when assessed by both cFIP and DRA factors. So while there are reasons to think the club could sustain its performance in terms of winning (the bullpen is one of the very best in the league at 3.22 DRA), overall one might expect the club to descend back to an average Runs Prevented performance. (Should this team continue to contend for the playoffs, they could be one particularly strange playoff team, basically driven solely by elite fielding and elite bullpen performances). (Yes, the Brewers fielding performance is very, very good.)

Table Three: Variance of 162 Game Extrapolation for 2018 Runs Prevented

This is not necessarily a knock on the Brewers, however. As the table above shows, extrapolating runs prevented figures over a 162 game demonstrates remarkable variance. There is really a statistical sense in which the baseball could land any which way, meaning that an average pitching staff could be expected to land within a wide range of outcomes the vast majority of seasons. The variance figures above are not necessarily foreign, nor are they solely due to extrapolation (even if extrapolation contributes some of the variance here); in 2017 NL, the average NL club of 0 Runs Prevented demonstrated Standard Deviation of +/- 100 runs, while the average AL club of 1 Run Prevented demonstrated Standard Deviation of +/- 91 runs. (Hence, aces do not exist.) Internal to their own range of MLB, league, cFIP, and DRA Runs Prevented extrapolations over 162 games, each team does not fare much better, with a typical variance of +/- 56 runs. This range should be intuitive when one considers a club like Milwaukee, where the club could indeed finish 124 runs better than average at their current pace, or decline to 2 runs below average at a harsher DRA pace.

If the Brewers pitching follows their DRA correction course, the offensive troubles of the club will be amplified over the course of the remaining season. Thankfully, the thawed out bats in May are producing runs at a generally average rate, meaning that the club could have a completely different look by the end of the season. Milwaukee’s likely range of Run Differentials is quite well defined even after only 44 games, which places the club in an intriguing position: while the bats provide rather obvious spots for improvement, depending on how the front office views the underlying pitching performances, the pitching staff could be a site for roster improvement as well.

Photo Credit: Jennifer Stewart, USA Today Sports Images

References:

Baseball Prospectus. Team Pitching – Standard. CSV retrieved May 17, 2018.
Baseball Reference. Team Standard Pitching [MLB, NL, AL]. CSV Retrieved May 17, 2018.
Baseball Reference. Three Year Park Factors. Retrieved from baseball-reference.com, May 17, 2018.

Stats:

MLB Runs Prevented: Based on MLB RA9 of approximately 4.45, and Three Year Park Factors (Baseball Reference). [(IP/9)*(MLB_RA9 * Park Factor)] – [Actual Team RA]

League Runs Prevented: Based on NL or AL RA9 and Three Year Park Factors. [(IP/9)*(League_RA9 * Park Factor)] – [Actual Team RA]

cFIP Runs Prevented: Based on NL or AL RA9 and Three Year Park Factors, plus each club’s cFIP according to Baseball Prospectus. [(IP/9)*(League_RA9 * Park Factor)] – [(IP/9) * (League RA9 * cFIP/100)]

DRA Runs Prevented: Based on NL or AL RA9 and Three Year Park Factors, plus each club’s DRA according to Baseball Prospectus. [(IP/9)*(League_RA9 * Park Factor)] – [(IP/9) * (DRA)]

162 Game Pace Stats: For DRA and standard RA/G, take either stat and do the following: [RA/G  * 162] or [DRA/G * 162]

DRA Correction: Building on current Runs Prevented, this stat estimates what a club’s final Runs Prevented would be if the remaining games follow DRA. [Current Runs Prevented] + [ (162 Game DRA Pace) * (Percentage of Remaining Games)]