The Red Sox optioned Kelly to Triple-A Worcester on Saturday, Julian McWilliams of The Boston Globe reports.
Kelly gave up three earned runs without recording an out during Friday's loss to the Yankees, inflating his ERA to 3.97 across 56.2 innings. He'll now head back to Triple-A, though there's still a possibility he makes another appearance in the majors before the season ends. He'll be joined in Worcester by Cam Booser while Bailey Horn and Zach Penrod come up from the minors to fill the open bullpen spots.