Domingo Tapia's heavy, sinking fastball has been traumatizing Minor League hitters since he signed with the Mets in 2009, but the 6-foot-4 right-hander's off-speed stuff, specifically his slurvy breaking ball, has been more of a work in progress.
Working with St. Lucie pitching coach Phil Regan, the Mets' No. 11 prospect has made notable strides with the pitch, according to St. Lucie skipper Ryan Ellis.
To that end, Tapia used the breaking ball regularly Sunday with success as he held Class A Advanced Daytona to two hits over six innings in St. Lucie's 1-0 victory.
"It's more of a curveball and it's come along nicely," Ellis said. "He's starting to trust it a lot more. Even when he's behind in the count, he's comfortable enough to mix it in. He's found control enough with it where he feels comfortable throwing it."
The development of his curve is a critical step for Tapia in his development, as it adds the crucial third offering to his repertoire.
The 21-year-old works his fastball around 93-94 mph with a hard sink. His changeup also has sharp diving action, helping him piece together an eye-popping 2.65 groundout-to-flyout ratio in the Class A South Atlantic League last year.
This year, his GO/FO is 1.77, and he's posted 28 strikeouts and 13 walks over 32 1/3 innings. He has a 2.23 ERA in seven starts and has only had one rough outing -- he allowed three runs in two-thirds of an inning April 11 against Palm Beach.
"If he can control that fastball with heavy sink and mix in his curve to the other side of the plate, it doesn't matter how hard he's throwing," Ellis said. "He's going to keep guys off balanced.
"He's absolutely confident with [the curve] right now. Hats off to him for that. That's a big part of his development."
Tapia ran into some trouble in the first inning, but catcher Albert Cordero bailed him out. After John Andreoli singled and Tim Saunders reached on a fielder's choice, Cordero caught Saunders trying to steal second base for the second out. Tapia walked Javier Baez, but Cordero picked Baez off first base to end the frame.
Tapia took over from there. He faced just two over the minimum over the next five innings, punching out Saunders to end the sixth before reaching his pitch count of about 90 pitches. He finished with four strikeouts and three walks.
Ellis has been impressed by Tapia's ability to rebound from turbulence, as he did following Sunday's first inning.
"I've noticed him progressing in a way," Ellis said. "He'll slow himself down, step behind the rubber and toss around the rosin bag and calm himself down. He's not pressing. He's slowing the game down and making adjustments to get himself back in the zone.
"I really didn't know anything about him coming into the season, but I've noticed that from his first start until now. At times, he'll still get a little quick with his body with his fastball, but he's been able to get himself back in tempo when he gets too fast."
Yeiper Castillo started for Daytona and countered with two hits and seven strikeouts over six scoreless frames.
Neither team scored until the ninth when St. Lucie took advantage of three consecutive walks issued by Luis Liria (0-2). After Cordero popped up with one out, pinch-hitter Matt Reynolds delivered a walk-off infield single.
Jake Seiner is a contributor to MLB.com. Follow him on Twitter at @Jake_Seiner.