The Story so Far, and Yet to Come: The 2019 Bullpen

Prior to the start of the 2019 season, many observers (including myself) projected the 2019 New York Yankees to have a historically great bullpen. The thought process behind those projections was sound. The Yankees had a historically great bullpen in 2018, and they brought back the core of it, while swapping out David Robertson for Free Agent import Adam Ottavino, who projected to strike out batters at a higher rate while allowing hits at a lower rate than David Robertson. The Yankees’ primary moves in the bullpen, bringing in Ottavino and re-signing Zack Britton, have largely paid dividends for the Yankees in 2019, but other elements of the core have proven fallible. Dellin Betances was never able to get going in Spring Training, and has remained on the IL throughout the season with what the team is calling a shoulder impingement, while Chad Green’s effectiveness has generally vanished.

Despite the surprises, the bullpen as a whole has been effective, even if it has not yet been historic in any way. Baseball-Reference credits the bullpen with 2.1 bWAR, while Fangraphs is more bullish on the Yankee bullpen, giving the group credit for 3.4 fWAR. The bullpen WAR leaderboards highlight the differences in the way in which each site evaluates pitching performance. Below, here is the WAR leaderboard from Baseball-Reference:

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Statistics tabulated and sorted courtesy of Baseball-Reference.

The bullpen WAR leaderboard from Baseball-Reference matches the eye test. Adam Ottavino has produced excellent results, while pitching in more high-leverage situations than every other Yankee bullpen arm not named Aroldis Chapman, according to Baseball-Reference’s leverage index measurements. The only blemish on Ottavino’s ledger is his unsightly 5.8 BB/9 ratio, but that is balanced somewhat by the fact that he allows just 5.2 H/9, has struck out 11 batters per 9 innings, and has maintained a 97.6% strand rate. Based on results, Baseball-Reference credits Ottavino with 1.4 bWAR

While Aroldis Chapman may not be achieving his statistics using the same methods as in years past, leaning far more on his slider while throwing fewer 100 MPH fastballs than at any point in his career, Chapman has displayed his customary stellar performance, solidifying the back of the bullpen with a 12.3 K/9, 2.8 BB/9 (his lowest walk rate since his first year in pinstripes), and a sparkling 1.40 ERA. Add it all up, and Baseball-Reference credits Chapman with 1.0 bWAR.

Baseball-Reference’s metrics view Zack Britton and Tommy Kahnle as the remainder of the bullpen core with regards to value. While neither have quite reached the level of value that Ottavino and Chapman have achieved this season, both have been above-average relief arms.

The drop-off after Britton and Kahnle is steep from a value perspective when looking at Baseball-Reference’s metrics. The 3 pitchers who have thrown the majority of the Yankees’ innings after the aforementioned bullpen core are Luis Cessa, Jonathan Holder, and Chad Green. Cessa has done very little to establish himself as a big league regular this season, and while he produces an above-average rate of strikeouts, he has done little else of value. That said, very little was expected of Cessa coming into the year. The bigger disappointment has been Jonathan Holder, and to a greater extent Chad Green. Holder has thrown the most innings of any relief pitcher this season (31.1 IP), but also has allowed hits at a high rate (8.6 H/9) and has a high ERA (4.88). Baseball-Reference’s metrics say that Holder has been worth -0.4 bWAR, which would look a lot worse if not for Chad Green’s performance. Chad Green was struggling enough to start the year that he was sent to AAA Scranton-Wilkes Barre to straighten his mechanics out. While Green has been a little better since his return to the Major League bullpen, the results have still been ugly overall, allowing 13.5 H/9 and an 8.27 ERA. Baseball-Reference hammers Green, crediting him with -0.8 WAR, making him one of the least valuable pitchers in baseball in 2019 by their metrics.

Overall, Baseball-Reference’s metrics indicate that the performance of the Yankee bullpen has been very top heavy, and much of the value of the core four bullpen arms have been given back by Cessa, Holder, and Green. Interestingly though, the story does not end there. Fangraphs’ metrics view the Yankee bullpen in a more positive light overall, but they also evaluate pitching performance very differently than Baseball-Reference. Take a look at the Fangraphs WAR leaderboard in the bullpen:

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2019 New York Yankees Bullpen fWAR Leaderboard, courtesy of Fangraphs.

The first name that jumps out here is Jonathan Holder. Based on his bottom-line performance, it seems crazy at first blush to see Holder in 2nd place on the Fangraphs WAR leaderboard with 0.6 fWAR. Holder does have solid strikeout and walk rates, and Fangraphs heavily weights those metrics that a pitcher can control. The other metrics that jump out are Holder’s 59.3% strand rate and .306 BABIP. Holder’s strand rate is strangely low, and his BABIP is a little high. These non-result driven statistics indicate that Holder has gotten unlucky through the first couple of months, and some positive regression could occur as the season wears on. Fangraphs credits Holder for his positive underlying statistics.

The other big name that Fangraphs rates differently is Adam Ottavino, who has only earned 0.4 fWAR. Despite his excellent results, Ottavino’s 97.6% strand rate and .230 BABIP are ripe for negative regression, and Fangraphs does not give Ottavino credit for his good luck thus far.

The final takeaway here is that Fangraphs does not see as much negative value performance as Baseball-Reference, nor does it view the bullpen performance as top-heavy in the way that Baseball-Reference sees it.

Personally, I prefer evaluating value based on performance metrics on the mound, so I tend to lean in favor of Baseball-Reference’s bWAR measurements, but I think that Fangraphs’ metrics are generally more predictive of future performance. To this point, I think that the bullpen performance has been top-heavy, but I think that the metrics show that some of the bullpen arms that have struggled to this point, like Jonathan Holder, may be ready to contribute more as the season wears on. Most importantly, outside of Ottavino, I do not see any candidates for significant negative regression, and even in the case of Ottavino, I do not believe that any regression will be severe due to his elite stuff. Even without some additional help, this solid group of bullpen arms is likely to perform even better as the season progresses.

Getting Healthy

The composition of the bullpen will change dramatically in the event that the pitching staff ever gets totally healthy this year. Let’s assume that at some point, all of Severino, Montgomery, and Betances gets healthy. The Yankees will need 3 spots on the pitching staff, and no one in the current starting rotation will be sent to the minors. This is the bullpen right now:

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Much as I like Hale, I think that he is an easy call to get DFA’d. Tarpley is a shuttle arm who can be easily dispatched. The choice then comes down to Green, Holder, and Cessa. There are enough positives in Holder’s underlying numbers that Holder is an easy choice to keep on the active roster. Complicating the choice is the fact that Cessa does not have any minor league options remaining, and would surely be lost if he were exposed to waivers. There is very little to recommend either guy in both the performance and underlying metrics. Based on the fact that pitching depth is good, I am in favor of sending Green to the minors if everyone gets healthy by the end of July, if the numbers look similar. Pitching depth is hard to acquire, and there is no reason to lose it in this situation by exposing Cessa to waivers.

The Yankee bullpen has been solid in 2019. The underlying metrics tell us that some of the bullpen arms that have struggled are due for positive regression, such that any negative regression from the core of the bullpen can be withstood. If Betances can come back healthy, and one of German or Montgomery fills a role in the bullpen in August and beyond, we could get to see the historically great bullpen we all hoped for this season, even if we didn’t get to see it for a whole season