NL Starting Pitchers Set to Break Out in 2021

March 19, 2021

Sam Chinitz identifies three National League starting pitchers who could break out in 2021 for fantasy baseball. These SP could be great value draft picks if they hold onto rotation spots.

With pitcher workloads diminishing and aces difficult to come by, finding breakout pitchers can make a significant difference for fantasy managers. Whether it be through a role change, a new pitch, a mechanical adjustment, or some other factor, plenty of pitchers break out each year and usually provide fantasy managers with excellent draft values along the way.

For this article, a breakout season is defined as one in which the pitcher has his most valuable fantasy season by a wide margin and is worth rostering in most leagues. The pitchers below have all had at least some (mostly unspectacular) major league experience and have the potential to take a big step forward in 2021.

It’s worth noting that the breakout definition is still fairly subjective, but it does rule out players like Corbin Burnes and MacKenzie Gore. With that in mind, below are three NL starting pitcher breakout candidates for the 2021 season.

Freddy Peralta, Milwaukee Brewers

Peralta was booted out of the Milwaukee rotation in 2019 after struggling to the tune of a 7.07 ERA over eight starts, and his bullpen role stuck in 2020 with Peralta starting only one game. Peralta has a chance to crack the rotation again in 2021 with Eric Lauer slotted in as the team’s fifth starter, though, and the 24-year-old’s successful 2020 performance points to a potential 2021 breakout.

Peralta’s 2020 season may not have seemed particularly impressive on the surface given his mediocre 3.99 ERA, but a strong 15.7% swinging-strike rate helped fuel a stellar 28% K-BB% and related 2.41 FIP. Importantly, Peralta made some significant adjustments to his arsenal last season that drove his improved performance, and those adjustments should carry over into the 2021 season.

To that end, Peralta re-introduced a slider into his pitch mix in 2020, and the pitch was a weapon with an impressive 21% swinging-strike rate and a 23% usage rate*. Combined with an already strong fastball that boasts a .305 xwOBA and a 14.6% swinging-strike rate for his career, Peralta’s slider gives him a formidable two-pitch arsenal. Add in Peralta’s usable curveball and he has a group of pitches that should allow him to be an upper-tier pitcher in 2021.

Peralta isn’t a perfect fantasy pitcher (nor does he have to be at his 330 ADP). His role is up in the air, his 6.1% HR:FB is unlikely to stay so low in 2021, and he might lose some effectiveness if he’s transitioned out of the bullpen. Still, it’s easy to dream on a pitcher with a fastball/slider combination like Peralta’s, and fantasy managers should target Peralta late in drafts as a breakout candidate as a result.

*Note: Baseball Savant and BrooksBaseball diverged on slider tracking for Peralta in 2020; Baseball Savant tended to group Peralta’s slider in with his curveball while BrooksBaseball was more liberal in separating the slider out. Because Peralta’s curveball measurements changed significantly in 2020 on Baseball Savant as an apparent result of the slider’s re-introduction and because his slider usage was so low on Baseball Savant (4.3%), I prefer BrooksBaseball’s slider definition and used BrooksBaseball’s measurements in this article.

Adrian Morejon, San Diego Padres

Joe Musgrove is the trendy breakout pick on the San Diego pitching staff, but Morejon has every bit of the breakout potential (and then some). It’s tough to beat Morejon from a pure “stuff” perspective; he’s got a fastball that touches triple digits and a trio of effective secondary pitches. Working together, Morejon’s arsenal is a work of art.

Adrian Morejon drew rave reviews from behind closed doors in Padres camp, and, uh, I get it. pic.twitter.com/n4HiE7m19r

— AJ Cassavell (@AJCassavell) August 18, 2020

Morejon is a little rough around the edges as his command could likely stand to improve, but he undoubtedly has enough talent for a breakout 2021. That said, Morejon still looks ready for a strong 2021 season with projection systems including ATC and ZiPS expecting a sub-4.00 ERA with a K/9 around 10.

Of course, rate stats don’t decide which pitcher is a more valuable fantasy asset on their own. Morejon will likely require injuries or a six-man rotation to see consistent starts, and it’s fair to wonder whether the Padres might keep Morejon on an innings limit in 2021 given their already stacked rotation and Morejon’s limited experience with a heavy workload.

Still, Morejon is loaded with breakout potential this season, and he should be on the radar of fantasy managers as a result. It doesn’t hurt that Morejon’s ADP is south of 400, and fantasy managers should target him at that price.

Tyler Mahle, Cincinnati Reds

Mahle made a bevy of adjustments coming into the 2020 season, including a mechanical tweak that provided his fastball with added velocity and spin. More specifically, Mahle’s fastball added just over 200 RPM in spin while making the pitch more spin-efficient, contributing to some additional vertical movement for the pitch. In addition to the pitch’s physical changes, Mahle also tended to locate his fastball higher in the zone than usual in 2020. It should be no surprise, then, that Mahle’s fastball’s swinging-strike rate jumped to a career-high 14% last season.

Mahle’s fastball improvements were far from the only notable changes he made in 2020, though. The introduction of an excellent slider (19.6% swinging-strike rate, .233 xwOBA) and a similarly valuable sinker (.243 xwOBA) provided Mahle with a pair of strong secondary pitches, and Mahle posted career-bests in his swinging-strike rate (13.8%), strikeout rate (30%), and xwOBA (.272) as a result.

All of that helped fuel Mahle to a solid 3.59 ERA in 2020, but his 10.5% walk rate leaves room for another jump in performance in 2021. Mahle’s relatively high walk rate was likely a product of his pitching approach to some extent, but his slider’s 40% zone rate was low and could likely increase without having a significant negative impact on its performance. Holding all else constant in 2020, Mahle’s FIP would have fallen 25 points to 3.63 with even a league-average walk rate (in line with his 8.5% walk rate coming into 2020).

It’s worth noting that expecting Mahle to replicate his 2020 performance but with an improved walk rate is optimistic. Mahle clearly has the foundation to take another significant step forward in 2021, though, and fantasy managers should keep that in mind on draft day.

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