Jennings, 27, had an 1.38 ERA, 3.48 FIP, 3.8 BB/9, and 8.5 K/9 in 47 games for Miami over 40⅓ innings. He has a 93+ mph four-seasmer and a mid-80s slider. He tends to be a groundball pitcher even with his fastball so fits the profile that the Sox look for in the bullpen.
While this looks good, there are some rough spots. He allowed 41% of inherited runners score last season. Also, lefties hit .289/.354/.403 off of Jennings while righties hit .238/.322/.389 for his career so his ability to be a LOOGY is a bit questionable.
Rienzo leaves the Sox after a disappointing 2014. After a strong start to 2013 at Charlotte, he joined the White Sox rotation after the Jake Peavy trade. Last season, he pitched 64⅔ with a FIP of 5.73. After giving up 10 runs in 2⅓ innings in three games in August, he was sent back to Charlotte without a September callup.