"He's one of us. You hate to see that," said Yankees closer Andrew Miller. "It's always a tough situation. For me, personally, I thought he was throwing the ball fine. He's just had a run of tough luck, and that happens. He'll be fine in the long run. It's sad to see someone go. He's friends with the other six guys out there, that's the way it goes. But he'll land on his feet and be fine."
Carpenter, 29, was 0-1 with a 4.82 ERA in 22 appearances for New York, including serving up a go-ahead RBI double to the Mariners' Austin Jackson in the sixth inning of New York's 5-3, 11-inning victory over Seattle on Tuesday.
"For whatever reason, he never got on a roll for us," Yankees manager Joe Girardi said. "At times, it was a struggle. He was someone that we expected to be a big part of our bullpen. He worked extremely hard, he was great in the clubhouse. It's just unfortunate."
Carpenter was acquired from the Braves along with left-hander Chasen Shreve in a New Year's Day swap that sent left-hander Manny Banuelos to Atlanta. Carpenter owns a 3.73 ERA in 210 career appearances with the Astros (2011-12), Blue Jays ('12), Braves (2013-14) and Yankees.
"Sometimes it's puzzling why things don't happen," Girardi said. "The guy worked and worked and worked; tried different things. We looked at a ton of different things to see if he was pitching different, sequences and everything. It really wasn't a whole lot different. The only difference was, he wasn't having success."
Trimming Carpenter leaves the Yankees with five left-handed relievers, which is something of an oddity. In addition to closer Andrew Miller, the Yankees are carrying Chris Capuano, Jacob Lindgren, Shreve and Justin Wilson.
"The one thing is, our lefties have been successful in getting right-handers out," Girardi said. "The bottom line is, if they get right-handers out as well as left-handers, you can deal with it. They've been pretty good at it."
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch, on Facebook and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.