John Brebbia lets it fly


For a two month period lasting from All-Star game until September 22nd, John Brebbia was arguably the St. Louis Cardinals best reliever. His 2.96 ERA trailed only Giovanny Gallegos and Ryan Helsley, and his 2.01 FIP was the bullpen’s best. A three game blowup at the end of the season soured his overall second half line, but for the most part Brebbia was great when it counted most.


While impressive, this run of success wasn’t necessarily anything new for the Cardinals reliever. Relying on his high octane fastball and slider, Brebbia is the proud owner of a 3.14 ERA over three season and 175 innings. His presence provided bullpen security in the 2018-19 offseason, and his talents caught the eye of Mark Saxon and Mike Shildt in early 2019. In other words, he was very much on the Cardinals radar even before his lights-out second half.


That ability to perform down the stretch in meaningful, high leverage games, however, has helped cement Brebbia’s position as a key bullpen piece going forward. Derrick Goold even mentioned him as a candidate to take on the closer role in 2020. Counting on any single reliever is a risky bet, but the Cardinals appear comfortable that some combination of their in-house options will suffice. Those possibilities include handing high leverage innings over to Brebbia.


On the mound, John Brebbia stands out from the crowd for more reasons than his late beard. He’s made his living as an extreme fly ball pitcher and, so far, he’s excelled by keeping those fly balls in the park. Last year, he went from June 20th to September 23rd without giving up a home run. Not giving up home runs is, obviously, good for a pitcher. All else equal, a pitcher who gives up fewer home runs will have a better ERA than a pitcher who gives up more home runs. Brebbia, by avoiding home runs, is doing a very good thing.


When evaluating players, though, I often think more about process than results. Usually, I’ll turn to FIP as a starting point to evaluate pitchers. FIP teases out batted ball luck to estimate a pitcher’s ERA based only on strikeouts, walks, and home runs allowed. Because it normalizes for batted ball luck, FIP is widely considered a better indicator of a pitcher’s true talent than ERA and, as a result, FIP “predicts” (correlates better with) a pitcher’s future performance better than ERA alone. For his career, Brebbia’s 3.39 FIP lines up pretty well with his 3.14 ERA. For 2019, his 3.13 FIP might indicate his 3.59 ERA was even a little unlucky. If we stop there, we leave the article thinking Brebbia is definitely-probably good.


The thing is, whether a pitcher allows a home run or not once the ball hits the bat and is launched in the air doesn’t have much to do with the pitcher. How many fly balls turn into home runs depends a lot more on who’s swinging the bat then who’s throwing the ball, and Brebbia allows more balls in the air than just about everyone.


Armed with the knowledge that pitchers can’t really control which fly balls leave the yard, we can take our evaluation of John Brebbia a step further. xFIP works just like FIP except that, instead of teasing out ball-in-play luck and taking home runs as a given, it takes the number of fly balls allowed and estimates how many fly balls would have been home runs with league average luck. Again, the “home run avoider” skill for pitchers is their ability to keep the ball out of the air, not to keep fly balls in the yard.


Using xFIP, we’re another step closer in our estimate of a pitcher’s true talent. With a better estimate of true talent, we can better guess how that pitcher will perform in the future. Keeping that in mind, here’s a chart:

That chart includes all relievers with 50+ inning pitched since 2017. Brebbia is the diamond (51.4%, 27.4%) and the color scale is xFIP. The redder the dot, the lower the pitcher’s xFIP. The lower the xFIP, the better we’d estimate that pitcher is likely to be in the future. Brebbia’s mark is blue, because his xFIP is bad.


How bad? In 2019, John Brebbia’s xFIP of 4.63 was more than a run worse than that 3.59 ERA. For his career, Brebbia’s xFIP of 4.44 is exactly 1.3 runs worse than his ERA. The difference between 3.14 and 4.44 is huge, and it might be the difference between Brebbia sticking in the majors and riding the Memphis shuttle. Complicating our perception of Brebbia through this lens is that, while it’s possible that some rare pitchers might have a skill to consistently outperform their xFIP, there’s no indication that Brebbia has it. In 230+ minor league innings, his ERA and xFIP are exact matches – 3.73.


Going back to the chart, there simply aren’t many pitchers in the majors with similar fly ball and strikeout rates as Brebbia. In part, that’s because of his own unique profile. It’s also, to some extent, due to survivorship – 54 pitchers have tossed ten innings since 2016 with a strikeout rate below 30% and a fly ball rate of at least 50%, but only thirteen of them have eclipsed 50 innings over that timeframe. Comparatively, about half of all relievers who reach ten innings also reached fifty in the period. It’s hard to maintain effectiveness while giving up so many fly balls when you’re not striking out a ton of batters.


If you buy into what I’m saying here, your view of Brebbia is probably getting more cautious. Here are two more charts which cast even more shadow:

Over the course of the season, and particularly in the second half, John Brebbia started allowing fly balls more frequently. Those fly balls mostly ended up somewhere inside the fence, at least in part because luck was on Brebbia’s side. At the same time, Brebbia was inducing hitters to swing and miss less often and, as a result, striking out fewer of them. There are plenty of ways to succeed as a reliever, but striking out fewer hitters while allowing more contact in the air isn’t typically one of them.


Why did he start missing fewer bats? My first inclination was to look at his slider and I found some fodder for a future post. Brebbia’s breaking ball has generally been effective, and his tendency to rely on it more in the second half of 2019 indicates that he thinks it’s a good pitch. That slider started to flatten out, though, losing a few inches of drop without being thrown harder or gaining any horizontal movement. According to Brooks Baseball, the spin axis shifted 10 degrees between the first and second half of the year, and the difference was even more stark comparing to prior seasons. That’s at least a starting point, and hopefully it’s one that Brebbia and the Cardinals are looking to address this spring.


Barring any surprise moves between now and the start of the season, the Cardinals will be counting on John Brebbia to handle bulk bullpen innings again in 2020. He’s not going to suddenly turn into a ground ball pitcher, but he could harness his stuff to consistently generate more strikeouts. If he doesn’t, he’ll have to hope his pitcher-friendly home park continues to keep those balls in the yard. Relievers are risky, and this one is showing some cracks beneath the foundation. The Cardinals are hoping John Brebbia’s house continues to stand.


Credit to @cardinalsgifs for the cover art, and to FanGraphs and Brooks Baseball for the data used throughout the post.