Pittsburgh Pirates: Robbie Erlin Could be an Underrated Reliever in 2020


After a rough 2019 season, this minor league signing could pay dividends for the Pittsburgh Pirates, and become an underrated relief pitcher for the team.

This off season, the Pittsburgh Pirates made a few moves. The biggest of these moves was trading Starling Marte to the Arizona Diamondbacks for Liover Peguero and Brennan Malone. One of the more moves that didn’t get much attention was when they signed former top prospect Robbie Erlin. But this signing might be one of the most underrated signings of the 2019-2020 off season.

Erlin was once ranked as one of the San Diego Padres best prospects. Baseball Prospectus placed him as the 53rd best prospect in baseball back in 2012. Despite making his debut in 2013, Erlin did not pitch all that much between 2013 and 2016.

During this four year stretch, the most games the lefty appeared in in a single season was 13, that coming in 2014. In 2015, Erlin mainly pitched in Triple-A, and appeared in just three MLB games, all of which were starts.

However, in 2016, after just 15.2 innings of work, Erlin would have to undergo Tommy John surgery. He missed the rest of the 2016 season, and all of 2017. At this point, Erlin did not have very much MLB mileage on his arm. He had pitched a total of 148.2 innings across four years, including 30 games and 25 starts.

However, Erlin returned in 2018 and put up pretty solid numbers. Through 109 innings, he served as a swing man, starting 12 of the 39 games he played. In total, he had a 4.21 ERA, but 3.31 FIP, and 1.13 WHIP. Impressively, he walked just 2.7% of the batters he faced, and had a solid 0.99 HR/9. While he wasn’t a big strikeout pitcher, his 20.7% strikeout rate was still solid considering how good he was at limiting walks.

Last year, the southpaw struggled more. In 55.1 innings, Erlin had a 5.37 ERA, but still solid 3.61 FIP, 6% walk rate, and 0.98 HR/9. He also posted the highest strikeout rate of his career in a full season of 20.7%. After the 2019 season, Erlin elected free agency. At the end of January, the Pittsburgh Pirates signed him to a minor league deal, but he has plenty of potential to be an extremely valuable member of the Pirates’ pen.

While Erlin has a career 4.57 ERA, he has strong ERA estimators. Those include a 3.59 FIP, 3.72 xFIP, 3.84 SIERA, and 3.86 DRA. That represents a pretty solid pitcher. His ERA estimators are very similar to that of Marcus Stroman, who has a 3.64 FIP, 3.59 xFIP, 3.83 SIERA, and 3.77 DRA throughout his career.

Erlin is a control master. He has only walked 4.8% of the batters he has faced throughout his career. That’s just 62 batters through 313 innings. 15 different pitchers walked more batters in 2019 alone than Erlin has across over 300 innings of work in his career.

Despite home runs being on a meteoric rise the last couple of seasons, Erlin doesn’t allow too many long balls. He has a career 0.98 HR9, and has let up 18 long balls in his past 164.1 innings of work. Not only did he have a 87.9 MPH exit velo last season, ranking in the top 69th percentile, but that combined with his 46% ground ball rate the past two years and you see why he isn’t giving up many home runs.

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Erlin got a bit unlucky last year with a .373 opponent batting average on balls in play. The MLB average was .296 and his career average was .303 before 2019. He would really benefit from the Pirates’ strong defense behind him. If he can stay healthy, I could see Erlin having a mid-3s ERA, and one of the more underrated relief pitchers the Pittsburgh Pirates have.