Think of it as one last big swing for the postseason.

With time expiring on their waiver claim of Jose Bautista, the Phillies completed a trade for the 37-year-old slugger by agreeing Tuesday to send a player to be named or cash to the New York Mets. Bautista is expected to be used off the bench.

Bautista becomes the sixth player acquired by the Phillies in the last 31 days. They added infielder Asdrubal Cabrera, catcher Wilson Ramos and lefty reliever Aaron Loup before the July 31 non-waiver trade deadline, then completed waiver deals for first baseman Justin Bour, lefty reliever Luis Avilan and Bautista.

To create a spot on the 40-man roster, the Phillies designated righthander Mark Leiter Jr. for assignment. Andrew Knapp was optioned to triple A to make room on the 25-man roster for Bautista.

"The role could be righthanded bat of bench, start in the outfield, deploy against lefthanders in the league and have a high degree of confidence that he's going to have a good at-bat for us," manager Gabe Kapler said. "He's going to be a veteran presence in the dugout and in the clubhouse. And I see a major part of his role being how intelligent he is. He sees the game differently than anyone we have on our roster right now. He's very good at picking up tells and figuring out which of our pitchers and opposing pitchers are tipping, and he's going to share that with our clubhouse."

Once considered among the most feared sluggers in baseball, Bautista is on the back nine of a 15-year career in which he has hit 342 home runs and posted an .836 OPS. The Phillies will be his third team — all in the National League East — this season. He batted .196 with 11 home runs and a .339 on-base percentage in 342 plate appearances between the Mets and Atlanta Braves, with whom he began the season in April after signing as a free agent.

"His track record and his pedigree in this game is one of the best in this clubhouse," Rhys Hoskins said. "So right away, that's what you think of. Obviously, he brings a clubhouse presence as well. Someone who's been through it before and can kind of guide us along the way."

Bautista played five positions for the Mets, who signed him in late May to a prorated contract for the major-league minimum salary. But he will be a free agent at season's end, giving him little value to the out-of-contention Mets.

"The leadership that he brings, the quality at-bats, I feel like he plays really solid defense at multiple positions," Mets manager Mickey Callaway told reporters Monday in Chicago. "I can definitely see why somebody would want to snatch him up, and give him a chance to be on a contending team."

The Phillies are hoping a big righthanded swing or two off the bench from Bautista will help propel them past the division-leading Braves and to their first postseason appearance since 2011. The Phils acquired lefty-hitting Bour for a similar reason. Bour is on the 10-day disabled list with a strained muscle in his left side.

Staff writer Matt Breen contributed to this article.