All of baseball is focused on a most precious 2 1/8 inches — the average length of the ulnar collateral ligament. This year, more than a dozen major league pitchers already have undergone Tommy John surgery — which involves replacing the elbow ligament with a tendon harvested from elsewhere (often the non-pitching elbow or forearm) in the patient's body. All-Stars Patrick Corbin, Josh Johnson and Matt Moore have had the surgery, and NL Rookie of the Year Jose Fernandez was scheduled to have his operation Friday.