During the game last Friday night, in which the Sox came away with an exciting 4-2 win against Oakland, Rick Hahn and Ben Cherrington worked out a deal that sends veteran left handed reliever Matt Thornton to Boston for power prospect Brandon Jacobs.

Thornton isn’t the All-Star caliber relief ace he was in the late 2000’s, but he’s a more than serviceable relief arm that the Red Sox need after the season ending injury to Andrew Miller. The instability of this bullpen is shown by the vast changes since opening day. Injuries to Miller and Joel Hanrahan and the reassignments of Clayton Mortensen and Alfredo Aceves have led to pitchers such as Junichi Tazawa being overworked. The Sox needed a reliable arm that could allow John Farrell to spread the workload around.

According to FanGraphs’ wonderful Pitchf/x data, Thornton’s fastball velocity is declining for the third straight season. This is typical of pitchers, especially ones in their mid 30’s, but Thornton is still able to reach back as he is averaging 94.2 MPH on his fastball this season.

Over his career, Thornton has shown that he’s capable of being more than a LOOGY, retiring right handers at about the same rate as left handers, but this season right handers are hitting .320/.414/.420 off of Thornton. Lefties haven’t been much trouble, hitting only .173/.232/.385. This kind of thinking can be dangerous though, as I am splitting small sample sizes into even smaller sample sizes.

The one thing that I notice when looking at Thornton’s platoon splits since 2010 is how mediocre his K/BB is against righties.

2010: 2.64
2011: 1.93
2012: 1.80
2013: 1.14

Those numbers are certainly not indicative of good performance, but it hasn’t been a problem until this season.

Andrew Miller’s role in the bullpen was that of a LOOGY, andThornton’s stats seem to signify that he’s been demoted to that roll now. I hope that Farrell will give Thornton some more work against right handers so he has a chance to normalize his large platoon split and maximize his value. According to MLBTradeRumors.com, Thornton is owed approximately $3.5 million the rest of the season. Alex Spier of WEEI reported Chicago footing $750k of it, meaning the Sox are on the hook for approximately $2.75 million, which is great value.

Brandon Jacobs is a high school power prospect taken in the 10th round of the 2009 draft. While Jacobs possess good raw power, he has a lot of miss in his swing, leaving him stranded in the minors until he can figure things out. Keep in mind that this is a White Sox farm system that rated 28th on Baseball Prospectus’ organizational rankings. While Jacobs isn’t much, he is talent and will probably be in consideration for the White Sox Top 10 Prospects list.