Adam Wainwright, last year's Cy Young runner-up, injured his pitching elbow. The Cardinals have indicated that it's a significant injury, with ESPN's Buster Olney tweeting that it "sounds like they are expecting Tommy John situation."
If Wainwright does indeed require Tommy John surgery, the Cardinals would be without their best pitcher. Wainwright finished last season with a 20-12 record and a sparkling 2.42 ERA. He gave the team 33 starts and 230 1/3 innings, and he finished second in Cy Young voting to Roy Halladay.