It’s official. The Red Sox have acquired Jake Peavy from the White Sox and reliever Brayan Villarreal from the Tigers as part of a three-team trade. The Tigers picked up shortstop Jose Iglesias from Boston. The White Sox are getting outfielder Avisail Garcia from the Tigers and three lower level prospects from the Red Sox: shortstop Cleuluis Rondon, RHP Francellis Montas and RHP Jeffrey Wendelken.

The addition of Peavy, who is owed $14.5 million next year, gives Boston added protection in case Clay Buchholz struggles to return from his neck problems down the stretch. It’s expensive insurance, though, with no guarantee that Peavy is much of an upgrade over Ryan Dempster or Felix Doubront in a projected four-man postseason rotation that also includes Buchholz, Jon Lester and John Lackey. Of course, the Red Sox have to worry about reaching the postseason first.

Peavy is 8-4 with a 4.28 ERA and a 76/17 K/BB ratio over 80 innings in 13 starts this season. He missed time earlier in the year with a broken rib. His biggest problem has been the home run ball — he’s allowed 14 — but switching from U.S. Cellular to Fenway will help there.

Iglesias, a Rookie of the Year candidate who was hitting .330/.377/.409 in 215 at-bats for the Red Sox, makes a great deal of sense for Detroit with Jhonny Peralta facing a Biogenesis suspension of at least 50 games. He gives the Tigers the rangy shortstop they need to put next to Miguel Cabrera, and while Peralta may get his job back at the very end of the year, there’s little doubt that it’ll be Iglesias next year, with Peralta presumably moving on in free agency.

The 22-year-old Garcia was talked up last year as a big piece of the Tigers’ future. His resemblance to Cabrera in the batter’s box probably helped in that regard. This year, he had hit .382/.414/.549 in 144 at-bats in Triple-A, but just .241/.273/.373 in 83 at-bats in the majors, and the Tigers deemed him expendable with fellow outfield prospect Nick Castellanos also knocking on the door. Plate discipline is an issue for Garcia, and while scouts expect his power to come, his high home run total in six minor league seasons is 14. Whether the White Sox use him right away could hinge on an Alex Rios deal. For now, though, he’s been optioned to Triple-A Charlotte.

The departure of Iglesias makes third base a question mark for Boston, fueling rumors that a deal for the Phillies’ Michael Young could follow. Barring a trade, the Red Sox will have to decide whether to promote Will Middlebrooks, Brock Holt or No. 1 prospect Xander Bogaerts from Triple-A to pair with or, more likely, start over Brandon Snyder at third. Bogaerts, a natural shortstop, is outhitting Middlebrooks in Triple-A, but he’s played just five games at third since getting a look there earlier in the month. The Red Sox also now have to weigh in the fact that Bogaerts is again clearly the shortstop of the future with Iglesias gone.

Villarreal, going from Detroit to Boston, has a 4.56 ERA and an 86/46 K/BB ratio in 75 innings as a major leaguer. He seemed to be on his way to emerging as a key piece in the Tigers bullpen last year, but control became an especially big problem late and he was left off the postseason roster. This year has been a disaster for him, but the fresh start could do him some good. He throws 94-98 mph, so he has some upside as a short reliever.

None of the prospects going from Boston to Chicago were viewed as key pieces of the Red Sox system. Rondon, 19, was hitting .276/.326/.350 in short-season ball. Montas, 20, was 2-9 with a 5.70 ERA and a 96/32 K/BB ratio in 85 1/3 innings as a starter for low Single-A Greenville. Wendelken, 20, had a 2.77 ERA and a 54/20 K/BB ratio in 65 innings as a reliever in low-A ball.

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