Motter was outrighted to Triple-A Worcester after clearing waivers Friday.
Motter lost his spot on the 40-man roster earlier in the week after Danny Santana and Enrique Hernandez returned from the COVID-19 injured list. The infielder didn't garner any takers on the waiver wire, so he'll remain in the Boston organization at Triple-A going forward. Motter has appeared in 16 big-league games with the Red Sox and Rockies this season, logging five hits (two XBH), one RBI and five runs scored across 29 plate appearances.