BoSox acquire lefty reliever Thornton

The Red Sox, getting a jump on the bullpen market, announced on Friday night the acquisition of left-hander Matt Thornton and cash from the White Sox for minor-league outfielder Brandon Jacobs.

Thornton, who turns 37 on Sept. 15, will give the Sox a second left-handed reliever to go with Craig Breslow. Andrew Miller is out for the season due to a left-foot injury, and another lefty reliever, Franklin Morales, remains on the DL with a strained left pectoral.

The White Sox included a cash payment of $750,000, as first reported by Thornton is owed about $3.5 million — the balance of his $3.5 million salary this season, and a $1 million buyout of his $6 million option.

Thornton no longer is as effective as he once was — his strikeout rate has declined from 12.0 per nine innings to 9.5 to 7.3 to 6.8 over the past four seasons. He has held left-handed hitters to a .173 batting average and .617 OPS this season, but right-handed hitters are batting .320 against him with an .834 OPS.

Jacobs, the Red Sox’s 10th-round pick out of Parkview (Ga.) H.S. in 2009, began the season at high A and recently was promoted to Double A. He has batted .265 with a .784 OPS in five minor-league seasons.

The White Sox were actively shopping Thornton and continue to shop righty Matt Lindstrom, who also is a potential free agent. The team, however, is unlikely to trade its closer, right-hander Addison Reed, who is under club control through 2017.

Righty Jesse Crain, a potential free agent who figured to be in the highest demand of any White Sox reliever, currently is on the disabled list with shoulder soreness.