Rob Biertempfel tweeted from Bradenton today that Jeff Karstens isn't throwing for a couple of days because he's being cautious with a sore shoulder. The whole thing is made to sound like it's not a big deal and that Karstens will be fine in a couple of days. That doesn't mean I'm not concerned, though.
Let's play detective here. The Pirates were unwilling to even tender Jeff Karstens a contract this winter, despite being due a relatively modest raise to the ballpark of $4 million. They were unable to trade him as the deadline to tender him approached. Karstens became a free agent, and no one wanted to touch him even though Kevin Correia got a two-year/$10 million deal from Minnesota. The market for him was so poor that Pirates re-signed him for $2.5 million, a $600k pay decrease from last year.
Presumably, part of the reason that there was such little interest in Karstens was his health. Karstens missed time in August of 2011 with a shoulder injury, then spent more than two months of the early part of last year on the disabled list with shoulder problems. Today, we get news about another sore shoulder. Literally just yesterday, Russell Carleton published a piece at Baseball Prospectus (no subscription required) about predicting pitcher injuries. You should read the whole thing, but the conclusion is that nothing predicts injuries better than previous injuries. Elbow injuries beget more elbow injuries and shoulder injuries beget more shoulder injuries.
Jeff Karstens has had shoulder issues two seasons in a row. Jeff Karstens already has shoulder issues a week into camp. This is pretty concerning, no matter how much it's being downplayed right now.