I am by no means an expert in this topic, but from some things I've been reading around the internet it seems that Nationals prospect Stephen Strasburg may be headed for serious arm trouble. As far as the analysis of mechanics go, I will leave that to ChrisOLeary.com.
"Arm Action: I don't like it. He starts his arm action with a pendulum swing, but has a bad "grab" as he tenses up his wrist and takes his elbow well beyond his acromial line in an attempt to "load" his scapula in a forced manner. He actually reminds me a lot of Mark Prior (gasp!)."
If you don't believe in mechanical analysis, we can also go to the statistics. I wont go into a scientific study of the following claims, but I will do a couple of quick cases.
First, some claim that pitchers who share the mechanics of Strasburg, such as Mark Prior, really get injured because they are frail. The second claim is that pitchers such as Prior don't get injured because they have bad mechanics, or because they are frail, but because they were overworked early in their careers. Let's see how these claims hold up.
With the first claim we face the difficulty of defining what frail means. Here frail certainly cannot mean its dictionary definition because I do not think at 6'5, 225 anybody would consider Mark Prior frail--I doubt any Major League pitcher in his mid-20s would fit anyone's definition of frail. So perhaps it has something to do with the pitcher's bone structure, his make-up, or something intangible. At the very least it is not something easily defined, and thus has weak predictive ability.
That said, for the sake of argument, let's assume Mark Prior is frail and that frail means someone of a body type similar to Mark Prior. Mark Prior's long string of injuries first began after throwing 5,426 pitches in the Major Leagues. Dan Haren has never spent an extended stint on the DL despite throwing over 19,000 pithces in his career. Dan Haren, at 6'5, 215, is perhaps more frail than Mark Prior. So what can explain the difference between the two? Perhaps we have picked the wrong measurement of frailty or perhaps it is because Mark Prior faced a heavy workload in the beginning of his career while Haren did not. We now investigate the second claim.
Mark Prior's Major League career began when he was 21. By the time he was 23 he had thrown 5,426 pitches. Mark Buehrle's career began when he was 21. After being 23 for several months, Mark Buehrle had thrown over 6,000 pitches. Mark Prior career has been riddled with injuries. Buehrle has never been on the DL for an extended period of time. It seems that Prior's injuries cannot simply be explained by the fact that he was overworked when he was young. We have eliminated frailty as well. Could the answer possibly lie in Prior's mechanics?
As I have said, the above does not constitute a scientific study. You could argue I cherry-picked Haren and Buerhle since they are two especially durable pitchers. But even then, the explanations of frailty and being overworked do not explain these cases while the mechanical analysis does. (You could argue I cherry-picked Prior too. Again, though, the explanations fail.) All of this is not to say that some pitchers are not too frail to play in the Majors or that overworking young players is detrimental to their health. I am arguing, however, that mechanics can provide far better explanations for the injuries pitchers face.
So keep this in mind, Nats fans, when partaking in Strasburg-mania. Whether we rush him or not, Strasburg's mechanics point to an injury-riddled career. Let's hope he's not frail to boot.