One Big Question: Can Martín Pérez build off 2019 changes for a 2020 breakout?

Welcome to Over the Monster’s One Big Question series. For those unfamiliar, this is something of a season roster preview where over the next 40(ish) (week)days we’ll be taking a look at each player on the 40-man roster prior to the season. If changes are made to the roster between now and Opening Day, we’ll cover the newly added players. Rather than previewing what to expect in a general sense, the goal of this series is to find one singular question — sometimes specific, other times more general — for each player heading into the coming season. We’ll go alphabetically one by one straight down the roster, and you can catch up with the series here. Today, we cover Martín Pérez.

The Question: Does Martín Pérez have a breakout coming in 2020?

The Red Sox have rotation issues, which is not a secret. Everyone knows what starting pitching is what will most likely define this season for the Red Sox, and while there are other issues with the roster it is the most glaring area that has the potential to keep them out of the playoffs. Chris Sale isn’t expected to miss more than a couple starts to begin the year, but while he’s out (and as long as everyone else makes it through camp healthy), Eduardo Rodriguez is the number one starter and *Insert depth arm here* is the number five. In the middle of the rotation is Martín Pérez, which is almost as concerning as the other facts considering his track record as a major-league starter.

The southpaw has been in the league for eight years now and, well, frankly he’s never been all that good. Pérez was a top prospect at the beginning of last decade, but injuries derailed his career early on. He’s been mostly durable since then, making at least 32 appearances in three of the last four years, but he’s also below-average in that time, and significantly so if you believe in a stat like DRA. Despite that, he was apparently a hot commodity this winter with the Rays — who, whatever you think of the way they run their franchise, know their pitching — vying for his services as well. Is there a chance he finally has his breakout as he gets ready to enter his age-29 season?

There are three reasons, at least as far as I can tell, to be optimistic about a breakout from Pérez. One of which is just looking at his pedigree, which I mentioned above. He made Baseball America’s top 100 prospects list a whopping five times from 2009 through 2013, making the top 50 once and topping out at number 17. I’m not super convinced by this, though, because the last time he made this list I was still in college. That was a long time ago. The second reason is more convincing, which is that he was once injured by a bull, beat his projected recovery time then killed and ate the bull. That guy is destined for greatness. Perhaps even more convincing than that, and the biggest reason the Red Sox and Rays were likely interested in him, are the tangible adjustments he made in 2019.

The changes revolve around his repertoire. For most of his career, Pérez has been generally a three-pitch guy, leaning mostly on a sinker, a four-seam and a changeup. The lefty also threw some breaking balls in there as well, but not as much as the other three pitches. Then, in 2019, he added a new pitch into the mix with a cutter and threw that more than any other pitch that season. The pitch did well according to Baseball Savant’s numbers, generating a 23 percent whiff rate with a .261 expected wOBA and a .272 actual wOBA.

It wasn’t just the cutter doing the work, either, although it certainly was the catalyst that led to everything. Pérez saw a massive shift in the quality of contact his opponents were able to produce. His average exit velocity dropped by three miles per hour down to 85.4, putting him in the top four percent of the league. Similarly, his hard hit rate fell by almost ten percentage points to 29.7 percent, putting him in the top seven percent of baseball there. That he still pitched to a 5.12 ERA indicates there had to have been some bad luck and he’s due for a turnaround, right?

Well, sort of. Luck is always part of the equation for pitchers, and it’s their job to put themselves in a position where it’s as small of a factor as possible. Pérez doesn’t do that. He doesn’t miss many bats, coming off a season with an 18 percent strikeout rate which was both a career-high and four percentage points below the league-average for starters. He also walked batters at a nine percent clip for a second straight season, compared to a 7.7 percent league average in 2019. If you’re not missing bats you’re, by definition, leaving more up to your defense and to fate, and if you’re putting guys on for free you’re in a position for that bad defense and/or bad luck to be costly more often.

In essence, what I’m saying is it’s possible to suffer from bad luck and also be to blame for the consequences. To put this into a little more perspective, I decided to look at how often pitchers like him can even be average. Using Baseball-Reference’s Play-Index, I searched for every season since 2012 (both Pérez’s first season and one of the years strikeout rates really took a jump around the league) in which a pitcher had a strikeout rate no greater than 18.5 percent and a walk rate no lower than seven percent with at least 150 innings. It should be noted that Pérez has never had a season with a K%-BB% this good, but those numbers represent something close to his career bests.

There were 103 such seasons in this span, and somewhat surprisingly there were 43 in which the pitcher was at least average by ERA+. Of course, this is something of a biased sample because if a pitcher is not doing well a team is less likely to give them 150 innings. Still, the Red Sox will need innings from Pérez, so it’s worth looking at how a pitcher can succeed with these kind of peripherals.

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He’s going to need that weak contact to work in his favor, which means he’ll need a low batting average on balls in play. The average BABIP among these 43 seasons that were at least average was .280. Pérez has never had a BABIP that low, although to be fair he’s never generated much weak contact until last season. The highest BABIP in one of these seasons was .330, and it was actually his 2017 season when he finished exactly average with a 100 ERA+.

Since the chances are, based on his track record, that he’s not going to have a strikeout rate and walk rate as good as the ones used in my Play-Index Search, he’s probably going to need to either allow a BABIP close to .280 or allow very few home runs. The latter is tough to talk about because, unfortunately. we have no idea how the baseball is going to fly in 2020. It is worth mentioning that, despite always being good at inducing ground balls, Pérez has allowed about an average rate of homers in each of the last three years. He’s also about to move to a division that is filled with hitter’s parks.

The more likely path to success for the southpaw is to keep a low BABIP, which is where that repertoire change came into play. Last season, comparing his batting average on difference types of batted balls (per FanGraphs) compared to the league average, Pérez was hurt most on low launch angle balls with grounders and line drives. That stuff is incredibly tough to predict year to year, particularly on line drives which are so subjective to categorize. A big part of it is likely to come down to defense on the left side of the infield, though, with lineups likely to load up with righties against Pérez. Devers and Bogaerts made strides with the glove last year, and their continued development could be more important to Pérez than any other pitcher.

With all of this said, I don’t really have a good answer. Pérez probably did get unlucky last year and the easiest way to buy into a breakout (whether it be by results or batted ball data or anything else) is for there to be a tangible change attached to it. That said, he still doesn’t help himself with strikeouts or walks, and it’s hard to see that changing. I’d like to see him throw even more cutters in the coming year and maybe miss more bats while getting that weak contact, but given his track record I’m in more of a “I’ll believe it when I see it” mode when it comes to a results-based breakout. That said, the bull thing does change the equation some.