Grant Balfour has been really good. Good enough to have a tRA of 2.20(!), and a tRA+ of 196(!!!): That's right, Balfour has been 96% better than the average AL Pitcher. So what has he changed? For one, his fastball has gotten a 1.5 MPH bump since last year, and he's been throwing it 15% more, to a total of 90% percent fastballs. By the way, lets see his FB against RHB, who he's been slightly better against then lefties.
Tough to make solid contact off of, as you can see from the foul balls, lets see the break: 
Balfour's Fastball breaks in on righties on the hands, the most a hitter could want to do with bloop it. Grant's go to pitch is a deathtrap against righties. His control has also been slightly better, so its not all velo and break, but its been very nice to see a guy who started the year in Durham perform like this. If he is willing to sign relatively cheap during the offseason, I'd definitely want to go for it before the relief ace position gets too expensive.