The standard rule of thumb for sniffing out elbow injuries is a decrease a pitcher’s control. Whereas a shoulder injury will likely reveal itself through a decrease in velocity, the elbow injury will manifest itself through a loss of command.
With that in mind, a more vigilant (read: paranoid) observer may have been able to detected Joe Nathan’s injury potential in the latter half of 2009, or at least raised the concern that maybe that tinge in your elbow might be a larger concern:
This trend was even more prevalent in the concluding portion of the season when his in-zone rate dropped to 40 percent and his walk rate rocketed to 12 percent. In addition to his decline in control, Nathan was getting slapped around harder than any other stretch of time in the past three years as his slugging percentage rose to .459 from August onward. This may have been indication that he was wild within the zone, missing his intended target and leaving a pitch far too hittable.
This drop in his command is almost certainly connected to the elbow problem revelation at the end of last season, which I discussed at some length in the Maple Street Press Twins Annual 2010. After the season, Nathan admitted that he was having elbow issues and was throwing at less than 100%. This prompted him to consult Dr James Andrews who recommended removing some bone chips.
It should be noted that bone chips/spurs are sometimes generated from a loose UCL. Basically, bones spurs start to grow on the elbow in the body’s attempts to stabilize the area caused by the collision of bone due to the loose UCL. This can be an early indication that future problems with the UCL are forthcoming. Because of this, combined with the in-season performance issues, Nathan’s injury is far from a surprise.
Dr Andrews may have informed Nathan that there was a probability of having UCL problems in the future during the original examine, or even that there were signs of tears, but simply removing the bone chips and hoping the UCL would hold up was the best practice at this juncture in his career. As with many pitchers before him, some feel significantly better after rest but then ultimately tear the UCL when attempting to throw above a 75% capacity (which was probably the case in his spring training outing). Knowing that Tommy John is basically a death sentence for his career thus really had to proactively pursue in the immediate offseason, rest and rehab were the only realistic options. Because of these series of events, the Twins seemed to have taken the right approach with Nathan.