Pitchers pitch, and sometimes after they pitch for a short while or a long while, they develop a tear in the ulnar collateral ligament in the throwing elbow. When the tear is partial, a pitcher can decide between trying to rehab, or going under the knife for ligament replacement, otherwise known as Tommy John surgery. They usually opt for Tommy John surgery. When the tear is complete, a pitcher needs Tommy John surgery.
Royals starter Danny Duffy was diagnosed with a torn UCL. He sought a second opinion, like they always do, but his fate was inevitable:
Kansas City Royals (@Royals) May 18, 2012
Used to be that Duffy was one of baseball's better stories, having gained two miles per hour on his average fastball. That was a week ago. Now we have to wonder about that added velocity. It's possible that Duffy's elbow couldn't take the added stress. It's possible this would've happened anyway, with or without the boost.
Duffy's done for 2012, obviously. If everything goes well, he could be back in the majors next April or May. The upside for the Royals is that Tommy John surgery usually doesn't end careers anymore, but a year without Danny Duffy is a year without Danny Duffy. That's a worse year.