Acquired along with minor league outfielder Drew Vettleson and catcher Jose Lobaton in the February 2014 trade that sent Nathan Karns to the Tampa Bay Rays, hard-throwing left-hander Felipe Rivero transitioned to bullpen work at the start of the 2015 campaign after starting in most of his minor league outings with the Rays from 2010-13 and all fourteen of his appearances for the Washington Nationals' affiliates in 2014.
The move put Rivero on a fast track to the big leagues. He was called up to make his major league debut in early April, and brought back in June.
In late September, the 24-year-old southpaw earned his first two saves in the majors in his final appearances of the season.
Now-former Nats' skipper Matt Williams talked about Rivero's sort-of out-of-nowhere rise through the organization ranks.
"Remember back to Spring Training," Williams said, "we sent him down to throw an inning get him up in the middle of an inning just to see how he would handle it. So I just think he's stepped forward and that's a good sign for him and a good sign for this organization."
"We think back to the inception of this, to his first day, not really coming out of the bullpen and thrust into it and he's done a great job and he will continue to do so.
"Couple innings the other night for the save and one today, just continues to go out there and throw strikes and help us win."
Rivero finished the year with a 2.79 ERA, a 2.64 FIP, 11 walks (2.05 BB/9) and 43 Ks (8.01 K/9) in 48 ⅓ innings over which he was worth 0.9 fWAR.
He averaged 95.5 mph with his fastball, topping out at 99.8 mph. Opposing hitters had a .226 AVG against his four-seamer and a .219 AVG against his two-seamer, which averaged 94.6 mph.
Hitters had just a .184 AVG against the left-hander's slider, which averaged 82.2 mph.
Williams, who sent him out in save situations in his last two outings, was asked if Rivero profiled as a closer going forward?
"It depends on how he progresses," he said. "His stuff profiles in any inning.
"Again, he's new to this, so first year out he's done pretty well and tonight's an example of what he can do. He can work through righties and lefties and go multiple innings if needed. So we'll see what the future holds."
Rivero held left-handed hitters to a .198/.242/.244 line and right-handers to a .198/.255/.344 line.
So where does he fit in the Nationals' 2016 pen? Oliver Perez, signed to a free agent deal this winter, seems to be in line to take the late-inning LOOGY role. Will Rivero work as a left-handed long man alongside right-hander Yusmeiro Petit? Will he fill a late-inning role as well, as a left-handed set-up man? Will Rivero end up closing one day?
The young, controllable southpaw impressed in his first major league campaign, can he follow that up with another solid season and help turn the bullpen, which was a weakness for the 2015 Nationals, into a strength in 2016?