Zeferjahn (4-4) allowed an unearned run on a hit and a walk while retiring two batters to take the loss in Friday's 6-5 extra-inning defeat to the Mariners.
Zeferjahn was tasked with working the bottom of the 10th inning in a 5-5 game, and he ended up serving up a walk-off single to Leo Rivas. It was the righty's first loss since he joined the Cubs at the trade deadline, with his last defeat coming back in May when he was with the Angels. Zeferjahn has struggled a bit with his new team, as he now has a 5.87 ERA and 1.96 WHIP across 7.2 innings in eight appearances. He does at least have a strong 12.9 K/9 in a Chicago uniform.