Acquired from the Cubs as part of the compensation for former general manager Theo Epstein, Carpenter started the season on the 60-day disabled list while recovering from right elbow surgery. He has made 16 appearances with Triple-A Pawtucket, going 1-0 with four saves and a 1.15 ERA. Triple-A batters were hitting just .137 off the 26-year-old.
"Very good, especially when he's down in the zone," manager Bobby Valentine said. "He's got a couple pitches that are pretty hard to hit when they're down. Good fastball, good slider. One-inning guy."
Carpenter allowed three runs in 10 appearances last season, walking seven and striking out eight.