While the Yankees did not trade for a reliever this summer, their already strong bullpen did add a quality arm in the middle of the season.
Adam Warren has excelled since being moved to the bullpen after Michael Pineda's return from the disabled list in June, as the 27-year-old righty has a 1.82 ERA in 24 2/3 relief innings this season. He has also averaged 8.8 strikeouts and 1.8 strikeouts per nine innings out of the bullpen.
"I've gotten comfortable with it and I feel like I've gotten into a rhythm the past few outings," Warren said of his transition to the role.
He struck out two in two scoreless innings in the Yankees' 3-2 loss to the Indians Thursday.
Warren had a 3.59 ERA in 14 starts this season, striking out 5.9 and walking 2.8 batters per nine innings. After Nova was recalled, Warren made his relief debut on June 30 against the Angels.
While he allowed a run in three of his first six relief appearances, Warren has been particularly effective since.
Over his last 12 appearances (dating back to July 18), Warren has an 0.96 ERA in 18 2/3 innings. He has struck out 8.2 and walked 1.9 batters per nine during this run.
"The first couple of weeks were more of a transition phase for me, just getting back to the routine of things and learning how to be a reliever again," said Warren, who had a 2.89 ERA in 69 relief appearances last season. "Once I kind of figured it out, it kind of came back to me from last year."
"Being able to be sitting down for six innings, get up and then go right into the game, that routine, getting back into that was the biggest adjustment," he added.
The new role has allowed Warren to pitch differently, including maxing out on his fastball velocity.
Warren's average four-seam fastball velocity has increased to 94.5 miles per hour from 93.2 mph since making the switch to the bullpen, according to the pitch tracking website BrooksBaseball.net.
"It plays up more out of the pen," Warren said of his fastball. "You can let it all out for one inning instead of trying to pace yourself for 100 pitches."
Warren joins a bullpen that came into Thursday ranked eighth in the majors in bullpen ERA (3.21), with a big-league best 27.1 percent strikeout rate. They had gotten 384 1/3 innings worth of work from their relievers, to rank seventh in the majors. Due to this combination of effectiveness and usage, Yankees relievers have combined to be worth an MLB-best 5.5 wins above replacement, according to the statistics website FanGraphs.com.
Dellin Betances (2.7 WAR) and Andrew Miller (1.3) have led the way, but for his performance over the last month and a half, they can also thank Warren.