From 2007 to 2014, 130 ulnar collateral ligament injuries of the elbow occurred in Major League Baseball players during the regular season. A significantly larger number (62%) occurred in the first three months of the season. Of the 118 players who pitched more than 100 innings prior to the injury, the mean fastball velocity was greater in the tear group (91.7 mph) compared with the control group (91.0 mph). Furthermore, relief pitchers made up a greater percentage of the early tear group (<100 innings) compared with the later tear group. Sixteen of the 170 UCL tears (9.4%) were recurrent tears.
Source: Orthopaedic Journal of Sports Medicine, February 2016