Rick Porcello has reportedly been traded to the Red Sox, according to a source. (Ed Zurga/Getty Images)

Sources: Red Sox add RHP Rick Porcello for OF Yoenis Cespedes, RHP Alex Wilson, LHP Gabe Speier

December 11, 2014 - 5:28 am

According to multiple major league sources, the Red Sox have traded Yoenis Cespedes to the Tigers in exchange for Rick Porcello. The Red Sox will also be sending relief pitcher Alex Wilson and rookie level left-hander Gabe Speier to Detroit. While the Red Sox had to include prospects, however, it's worth noting that Porcello can be extended a qualifying offer for the purposes of gleaning a draft pick as compensation should he leave after the season as a free agent; Cespedes is not subject to a qualifying offer. News of the Cespedes-for-Porcello framework was first reported by CJ Nitkowski of Fox Sports 1. Porcello gives the Sox a second durable addition to their starting rotation following the (almost-completed) addition of left-hander Wade Miley from the Diamondbacks on Wednesday. The 25-year-old went 15-13 with a career-best 3.43 ERA and career-high 204 2/3 innings in 2014, a step up from his first four seasons in which he'd posted a 4.51 ERA while averaging 174 innings a year. However, his breakthrough may have had as much to do with the defense behind him as with his own work on the mound. A pitch-to-contact sinkerballer, Porcello had suffered for years as a result of a Tigers infield that had myriad defensive deficiencies. The team upgraded in 2014, with Nick Castellanos taking over at third for Miguel Cabrera, Cabrera moving to first and Gold Glove candidate Ian Kinsler joining the club as a second baseman. The result was a year in which Porcello's actual ERA reflected the kind of contact that he elicits, as well as the frequency of his strike-throwing (he averages 5.5 strikeouts and just 2.2 walks per nine innings in his career). Cespedes, acquired for Jon Lester and Jonny Gomes at the trade deadline in 2014, his .260/.301/.450 in 2014, including .269/.296/.423 with the Red Sox over the final two months. He showed above-average range in left field when playing in larger outfields, though he struggled with the nuances of Fenway's left field wall. And with the Sox' signing of Hanley Ramirez to play left field for the next four years, Cespedes' only fit with the team in 2015 would have required a move to center or right fields. His trade helps to address what had become a growing outfield surplus; the Sox now have Ramirez, Rusney Castillo, Mookie Betts, Allen Craig, Shane Victorino and Daniel Nava (as well as minor league depth options like Jackie Bradley Jr. and Bryce Brentz) for the outfield. Wilson, a 2009 second-round pick who turned 28 in November, performed well out of the Red Sox bullpen in 2014. He appeared in 18 games with a 1.91 ERA in 28 1/3 innings, striking out 6.0 but walking 1.6 per nine innings. Speier, a 2013 19th-rounder out of high school who underwent Tommy John surgery shortly after turning pro, had a strong return from the procedure as a 19-year-old in the Rookie Level Gulf Coast League, going 3-0 with a 1.55 ERA with 26 strikeouts, just one walk and excellent groundball rates in 29 innings. Porcello and Miley give the Sox a pair of mid-rotation starters who have proven durable throughout their careers (Miley has three straight years of 198 or more innings; Porcello has averaged 30 starts a year in his big league career) to offer scaffolding for Clay Buchholz and Joe Kelly, who have not demonstrated their durability as starters. MLBTradeRumors.com projects Miley to earn $4.3 million next year and Porcello to earn $12.2 million, meaning that the Sox likely have both the payroll flexibility and prospect resources to make further additions to the pitching staff either via free agency or a trade.