Yarbrough (11-5) gave up six runs on eight hits and one walk while striking out two through 3.1 innings to take the loss against the Red Sox on Sunday.
Yarbrough endured a disastrous first inning in which he allowed six hits, including a three-run home run, before running into trouble again in the fourth frame. The 27-year-old has a 4.08 ERA with 114 strikeouts through 27 appearances this season. Yarbrough is scheduled to make his next start Saturday against the Blue Jays at Rogers Centre.