Winckowski was optioned to Triple-A Worcester after Thursday's loss, Chris Cotillo of The Springfield Republican reports.
Winckowski returned to Triple-A after he gave up six runs on seven hits and a walk over five innings against the Pirates on Thursday. The right-hander owns a 5.19 ERA and 1.50 WHIP with 36 strikeouts over 60.2 innings in 12 starts for the Red Sox this year. The transaction opens a roster spot for Matt Strahm (wrist), who's expected to be activated from the 15-day injured list Friday.