Robert Gsellman burst onto the scene in 2016 when injuries to the Mets pitching staff during the height of the wild card race thrust the righty into a prominent role. In the 44 2⁄3 innings Gsellman pitched down the stretch, he was very impressive, with a 167 ERA+ over that span. Prior to the 2016 season, Gsellman was not a standout prospect and struggled to strike batters out in Double-A, but an uptick in velocity on his fastball and the addition of the Warthen slider transformed him into an effective pitcher at the major league level.
However, Gsellman took a rather large step back in 2017. He had an up-and-down first half before pulling his hamstring in late June trying to beat out a grounder to first base. While his overall numbers from last season look pretty ugly on almost all fronts, he did improve after returning from the disabled list, posting an ERA of 3.50 in 8 starts in the second half.
His struggles last season combined with the signing of Jason Vargas probably add up to Gsellman starting off the season in Triple-A, if things break right for the Mets out of camp. However, for a team that has as many pitchers with robust injury histories on its staff as the Mets do, having a pitcher that has seen big league success like Gsellman waiting in the wings is extremely valuable. Both Steamer and PECOTA foresee Gsellman getting over 80 innings of work with the Mets this season, with 4.56 and 4.78 ERAs, respectively.
Time will tell whether Gsellman’s difficulties will persist or if last season’s effort can simply be chalked up to a sophomore slump and an injury setback.