The Washington Nationals acquired Felipe Rivero as part of a 3-for-1 trade with Tampa Bay last winter (2013-14) which sent right-hander Nathan Karns to the Rays in return for the left-hander, catcher Jose Lobaton and outfield prospect Drew Vettleson.
Nats' GM Mike Rizzo told MASN's Dan Kolko at the time that he and his scouts had good reports on the left-hander:
"'[W]e've got very, very strong reports on him,'" Rizzo said. "'He's pitched at 21 years old in the Florida State League, throws 95, 96 (mph), he can spin the breaking ball and he's got a huge upside.'"
Rivero spent the majority of his first season in the organization at Double-A Harrisburg, where the left-hander was (2-7) in 10 starts with a 4.12 ERA, 4.18 FIP, four home runs allowed (0.82 HR/9), 18 BB (3.71 BB/9) and 38 Ks (7.83 K/9) in 43 ⅔ IP though he dealt with elbow issues which limited his action.
In five Spring Training outings this year, before he was optioned to Minor League camp in early March (and eventually assigned to Triple-A Syracuse), Rivero threw 5 ⅔ scoreless in which he walked no one, struck out six and held opposing hitters to a combined .211 BAA.
He apparently made quite an impression in his brief time with the big league club:
Nats optioned lefty Felipe Rivero after today's game. "Really opened some eyes this spring," Matt Williams said.— Dan Kolko (@masnKolko) March 16, 2015
Rivero worked out of the pen in three appearances at Triple-A to start the season, giving up three hits, a walk and three earned runs in his first outing.
Washington Post writer James Wagner reported this morning that "two people familiar with the situation" told him the Nationals were calling Rivero up to the majors after finishing the series in Boston with only one left-hander (Matt Thornton) in the bullpen after the Nats designated Xavier Cedeno for assignment earlier this week.
The Nationals made the move official this afternoon, optioning Taylor Jordan to Triple-A after he was called up yesterday and bringing the now-23-year-old Rivero up to the majors:
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