BOSTON (AP) — The biggest trade of the Major League Baseball season was completed on Tuesday with pitcher Jake Peavy moving from the Chicago White Sox to Boston in a deal that also sent shortstop Jose Iglesias to Detroit.

The slick-fielding Iglesias provides a nice insurance policy for AL Central-leading Detroit in case Jhonny Peralta is suspended as part of baseball's Biogenesis drug investigation. Iglesias also can play second and third.

"The frank reality is that I do not know what is going to happen with Jhonny, but with this move, we now feel well protected if there is a long suspension," Tigers general manager David Dombrowski said.

"We didn't feel we were well protected in that situation with our internal options. If it were a 15-day thing, like a typical injury, we could have comfortably dealt with it with the players we already have, but when you start to talk about 50 days and a possible playoff run, we feel better going ahead with Jose."

Peavy is 8-4 with a 4.28 ERA in 13 starts this season. The 2007 NL Cy Young Award winner was considered the best starting pitcher on the market ahead of Wednesday's non-waiver deadline.

"If there's one thing we wanted to do — if we could pull it off — is to add a starting pitcher as we look at the next two months," Boston general manager Ben Cherington said.

Peavy tweeted a message to White Sox fans after the deal was done:

"THANK YOU Chicago! It's been an honor & a privilege to pitch for u! You are 1st class & I will never forget you! So many emotions right now!"

With Clay Buchholz on the disabled list with a shoulder problem, the move gives Boston another proven starter for the run toward the playoffs. It also could strengthen the bullpen if the Red Sox decide to return rookie Brandon Workman to a relief role if Buchholz comes back.

"We thought Peavy, of the starting pitchers available, was the right fit for us," Cherington said. "It just came together that this was the deal we thought made the most sense."

The Red Sox also got reliever Brayan Villarreal from the Tigers. They shipped Iglesias to Detroit and three minor leaguers to the White Sox as part of the trade.

Chicago also received prized prospect Avisail Garcia. Garcia, who turned 22 in June, hit .374 with five homers and 23 RBIs in 33 games for minor league Toledo.

The outfielder, who was the Tigers' minor league player of the year last season, was assigned to Charlotte.

"We're very excited about his upside," general manager Rick Hahn said. "We truly feel this is a five-tool player, someone who's not only going to hit for average but for power, run well, play above-average defense.

"He's still young and he still has a little bit of development ahead of him, but we feel we've acquired someone with a great deal of upside who's going to have a big impact on the South Side for many years to come."

Peralta is among a group of players who have been linked in media reports to Biogenesis, a closed Florida anti-aging clinic that was accused by Miami New Times in January of distributing banned performing-enhancing drugs, sparking an investigation by Major League Baseball. The league could hand down multiple suspensions as part of the case in a matter of days.

The 23-year-old Iglesias hit .330 with a home run and 19 RBIs in 63 games with the Red Sox, who trail division-leading Tampa Bay by half a game. He was the AL rookie of the month for June, when he batted .395 with six RBIs.

"Jhonny Peralta is our shortstop until someone tells us he can't be our shortstop," Dombrowski said. "If that happens, we are very comfortable with Jose going forward, but until then, we have a talented young player who can play second base and third base very well."