Mariano Rivera, New York Yankees: Who knew the routine of shagging fly balls during batting practice would be the thing that would undo the remarkable run of health Rivera has enjoyed? Unfortunately, that was precisely the activity that ended Rivera's 2012 season prematurely when he suffered a torn right ACL as a result. Rivera underwent reconstructive surgery in mid-June (there was a slight delay when Rivera developed a blood clot in his leg) but everything about his recovery has been absolutely on track to ready him for the start of the season. As early as January, Rivera declared his knee about "95 percent" healthy, according to Bryan Hoch of MLB.com, and he has been on a throwing program since mid-January. He faced his first live hitters in late February but has yet to throw in a game situation. That is not likely to happen until some point in mid-spring training. Games will require Rivera to react to things like balls being hit squarely in his direction or defensive situations requiring him to run and cover a base or spin quickly and make a throw. There is no reason his knee won't be ready to handle those scenarios but each bump in activity places a new, higher level of demand on him and his leg and confirms his readiness to move to the next level.
Don't let the age of 43 be a deterrent; this is one athlete who has retained an amazing level of health and fitness throughout his career. Naturally when it comes to pitchers there is no guarantee that the throwing arm won't present a problem, but even in that department Rivera has remained relatively unscathed throughout his career. His reconstructed ACL on his push leg should not be an issue into the season, especially as he adapts to the feel of pitching over the course of spring training.