Former Boston Red Sox manager Bobby Valentine on Tuesday said slugger David Ortiz sidelined himself after a brief return from an Achilles injury -- not because of soreness but because the team made a blockbuster deal that sealed its playoff fate.

Ortiz was on the disabled list from July 18 to late August with a strained right Achilles. He went 2 for 4 with two RBIs in a one-game return Aug. 24. The next day, the trade that sent Adrian Gonzalez, Josh Beckett, Carl Crawford and Nick Punto to the Los Angeles Dodgers was made official.

The Red Sox were 60-66 on Aug. 24, 13½ games behind the Yankees in the AL East and 8½ out of a wild-card spot.

"He realized that this trade meant that we're not going to run this race and we're not even going to finish the race properly and he decided not to play anymore," Valentine said in an interview on "Costas Tonight" on NBC Sports Network. "I think at that time it was all downhill from there."

Ortiz returned to the disabled list on Aug. 27 and never left it.