http://blog.nj.com/ledgeryankees/2007/0 ... stens.html
One reason Jeff Karstens has impressed this spring is that his fastball is up to 91 mph. During his call-up late last season, Karstens was at times throwing only 86 mph.
He attributes the increase in velocity -- which also helps the deception of his change-up -- to a couple of factors. Working out at Athletes Performance Institute, the 6-foot-3 Karstens put on 15 pounds, going from 175 to 190.
Another factor is eliminating the cut fastball from his repertoire. Karstens believes throwing cutters last year contributed to a sore elbow that robbed him of velocity.
42 IP - 3.80 ERA - 1.20 WHIP - 16 SO - 11 BB in 2006 while lacking strength in his fastball. A 91 mph fastball with his seemingly great control could mean good things in the future for him.
By no means am I talking about top pitching material, and yes, it's only ST, but he might be someone to keep an eye on midyear when you need a 5th starter on your team.