The Cardinals have acquired John Lackey from the Boston Red Sox, per CBS Sports' Jon Heyman. Lackey had asked for a trade Wednesday afternoon per SoxSpace's Jared Carrabis, and the Red Sox were quickly able to oblige. In return, as first reported by Peter Gammons, the Red Sox will receive outfielder/first baseman Allen Craig and pitcher Joe Kelly. WEEI's Alex Speier reported that minor league lefty Corey Littrell, Boston's fifth-round pick in 2013, will also head to St. Louis in the deal.

St. Louis, which added Justin Masterson to its rotation via trade on Wednesday, has now brought aboard two starters for the stretch. Boston, for its part, has now dealt two of its top starting pitchers in one day, with the Lackey trade close on the heels of the blockbuster that sent Jon Lester and Jonny Gomes to Oakland for Yoenis Cespedes.

Lackey bolsters the St. Louis rotation considerably while providing low-cost depth for 2015 due to a clause in his contract that stipulated a $500,000 salary next year in the event that Lackey underwent Tommy John surgery, which he did in 2011. The Cardinals need that depth, too, as the loss of Michael Wacha and Jaime Garcia to shoulder injuries has thinned their rotation.

It's been rumored that Lackey will seek to renegotiate his 2015 salary, using retirement as potential leverage, but it seems likely that a new deal can be reached giving Lackey more money in the short term, and the team a favorable deal in the long term. Lackey is scheduled to be a free agent following the 2015 season, assuming that option is utilized.

With a second consecutive season posting an ERA in the mid-3.00s and a FIP to back it up, Lackey has legitimized his return from Tommy John. He is posting eerily similar numbers compared with 2013, with strikeout, walk and ground ball rates all within half a percentage point of last year's figures, and except for a small scare early last year, he has been as durable as ever.

Boston is making a buy-low move on Craig, who has struggled through a frustrating 2014 season after emerging as one of the more underrated and productive hitters in the National League back in 2012. Craig, who will be paid around $1.8 million for the rest of this season, is owed $25 million over the next three years, with a $13 million team option or $1 million buyout in 2018. While that's a very reasonable price for a player with .876 and .830 OPS over his last two campaigns, Craig has struggled to a .638 OPS in 97 games this year.

Kelly, a 26-year-old righty, has been an effective presence at the back of the rotation for the Cardinals since 2012, although his recovery from an April hamstring injury has limited him to just seven starts on the season. With just one full season and parts of two others at the big league level, Kelly won't be eligible for arbitration until 2016 and is under team control until 2019. He should provide a cost-effective replacement for Lackey in the present, and could be a potentially useful trade piece down the road should Boston's heralded pitching prospects crowd him out of the rotation.