With a 7-4 lead after six innings on Sunday, Washington Nationals' manager Matt Williams sent Felipe Rivero to the hill to take on right-handed hitting pinch hitter Miguel Rojas and left-handers Dee Gordon and Ichiro Suzuki. Three ground ball outs and 12 pitches, 10 of them strikes, later the rookie left-hander was through a quick scoreless frame, acting as the bridge to Drew Storen and Jonathan Papelbon, who finished off the series finale with the Miami Marlins.
When he was done for the day, Rivero, 24, had a 2.73 ERA, a 2.70 FIP, five walks (1.36 BB/9) and 29 Ks (7.91 K/9) in 31 games and 33 innings pitched.
The former Tampa Bays Rays' prospect, acquired along with Jose Lobaton and minor league outfielder Drew Vettleson in a February 2014 trade for right-handed starter Nate Karns, has held left-handed hitters to a .211/.237/.263 line, and right-handed hitters to a .257/.297/.449 line in his first full season as a reliever.
Rivero's fastball averaged 97 mph and got up to 98.8 mph on Sunday, and he mixed in a few sliders that averaged 82.7 mph and got up to 84.4 mph.
Williams talked late last month about the transition Rivero has made.
"It's a little bit different mentality out of the bullpen," he said.
"He's been a starter for the majority of his minor league career, which means that he's got to conserve as he goes deep in a game. He doesn't necessarily have that worry at this point. So tonight it was really good. 97 mph fastball. That's the best fastball we've seen him have and some breaking balls for strikes to get ahead as well."
The second-year skipper talked about that transition again on Sunday afternoon, after another impressive outing by the lefty.
"Felipe was good against the lefties," Williams said. "The way their lineup sets up today anyway, he was able to get in there for the seventh, and then turn it over to [Storen] and [Papelbon]."
Asked what he's seen from the hard-throwing southpaw, who's held opposing hitters to a .266 AVG on his fastball and a .194 AVG on his slider this season, Williams said he's been impressed with the progress Rivero has made.
"What I see is a guy that's made a good transition from being a starting pitcher to a late reliever," Williams explained.
"Any time you want to think about doing that with a starter, you hope that the fastball ticks up. His has really ticked up. Today at 98 mph. So, 98 from the left side is pretty special. Good feel for a breaking ball today.
"So he's learning that," he continued.
"He's getting better and better at that. And we put him in some situations this year where he's had to face righties as well and he's done fine. So, he brings that experience from starting and the lefties, he's been really good against."
There are surprising rookies on the roster this season, with Michael Taylor getting more at bats than expected due to injury and Clint Robinson sticking in a variety of roles, at 30 years old, but Rivero might be the biggest revelation of the season.
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