Robert Gsellman has been one of the Mets' most valuable weapons in the bullpen this season, and manager Mickey Callaway believes a lot of that has to do with Gsellman's attitude and desire to learn.
"When I told him and we relayed the message to him that he was gonna be going to the pen, he embraced it from day one," Callaway told SNY's Steve Gelbs prior to Monday night's win over the Marlins at Citi Field. "And you have to do that to have success. And I think that's why he's having success."
"He was excited about it," Callaway continued. "He goes out there and he pitches an inning in relief and he comes off -- even his first inning in relief in spring training -- he came off and said 'I love this.' So that right away gave me at least the confidence to go 'you know what? He's gonna be pretty good in this role and we're gonna run him out there.'"
The 24-year-old Gsellman -- like Seth Lugo -- is adjusting to his full-time bullpen role on the fly. And while he is excelling -- with a 2.76 ERA and 1.19 WHIP to go along with 28 strikeouts in 29.1 innings (21 appearances), Gsellman is still learning.
"I think early on he would come out of the 'pen, you know, just feed guys fastballs like he was starting a game," Callaway said. "And when you're a reliever, you have to mix it up a little bit. Even if you have to throw a first-pitch breaking ball to the first batter you face, that's what you have to do. And he's done a really good job of making that adjustment."
And Gsellman has been mixing it up more, throwing his slider a career-high 21.1 percent of the time and his fastball a career-low 55 percent of the time (down from 63.2 percent last season).
The converted Gsellman and Lugo have been key weapons in the bullpen, but the Mets are dealing with uncertainty in the back end of their starting rotation -- something that isn't lost on Callaway.
While Callaway has pondered whether it would make sense to move Lugo back into the starting rotation in order to shore it up, he hasn't said the same about Gsellman, who seems to have found a home in the bullpen.