BRADENTON, Fla. -- Ray Searage was sitting behind the catcher in the LECOM Park's bullpen last week, expecting a fastball to zip out of Felipe Rivero's left hand. As Searage ducked to protect himself from the seemingly off-target pitch, it quickly dropped into the strike zone.
It was a high-spin curveball, probably the fourth-best offering in a deep arsenal highlighted by Rivero's high-octane fastball and swing-and-miss changeup. Throw in a sharp slider -- opponents hit .130 against it last year -- and the occasional knee-buckling curveball, and it's not hard to see why the Pirates targeted Rivero last year.
"The curveball is nasty. The slider is nasty," Searage said. "It's unbelievable."
The July 30 trade that sent Mark Melancon to the Nationals may not have been popular in Pittsburgh, but it brought back hard-throwing prospect Taylor Hearn and a potential closer in the 25-year-old Rivero, who is under club control until 2022. Rivero will be a key part of this year's bullpen, setting up closer Tony Watson along with right-hander Daniel Hudson.

What makes Rivero effective? Start with his four-seam fastball, which last season averaged 96.4 mph. He was one of three left-handers in baseball, along with Albertin Chapman and James Paxton, to hit 100 mph in 2016.
Rivero said he threw 86 mph when he signed -- as a 150-pound kid out of Venezuela -- with the Rays in July 2008. He put on weight over the years, and he was touching 96 mph as a starter in Tampa Bay's system.
The Nationals acquired Rivero in 2014 and moved him to the bullpen in '15. Pitching in shorter bursts, not conserving his strength for later innings, his arm sped up. By his second month as a reliever, he said, he was hitting 98-99 mph.
"And they were like, you're not starting anymore," Rivero said. "They saw that. I don't want to go back to starting. The adrenaline that you have coming in late in the game, it's not the same. I want to stay in the bullpen for a long time."
Rivero learned his two-seam changeup grip from Jorge Moncada, a former Minor League pitching coach with the Rays. He hasn't changed it since and says that consistency is "what makes it where the hitters can't hit it."
He's not wrong. Rivero's changeup may have been the Majors' most unhittable pitch last year as MLB.com's Mike Petriello wrote. According to Statcast™ data, he threw 101 changeups for the Pirates and opponents swung at 43 of them. The results: 27 swinging strikes, 11 foul balls and five balls in play (three singles and two groundouts). 

The one drawback is Rivero's control. He walked 18 batters in 27 1/3 innings with the Pirates last year, and he's averaged 3.2 walks per nine innings in the Majors. Searage and Rivero have identified the solution: If Rivero keeps his head straight and his front shoulder closed, he won't fly open, fall off the mound and spray the ball outside the strike zone.
"My goal this year is to keep it simple, not try to throw 105 or something like that," Rivero said. "Just keep the ball over the plate."
Watson, a free agent after this season, is Pittsburgh's closer. Hudson, signed to a two-year deal, has experience in that role. Whenever the opportunity presents itself, Rivero will be ready to take on that title.
"Probably in the future," Rivero said. "I'm not worried. I know it's going to come one day. I'll be here."