While brushing up on my knowledge of hamstring strains this morning for the front-page post, I stumbled upon this May 2010 post from Will Carroll on an Edgar Renteria hamstring strain that does, I think, shed a little bit of light on how hamstring strains can vary in severity:
Edgar Renteria (strained hamstring, ERD 6/15)
The difference between who someone is and who we think they are is often pretty big. A lot of people still see an elite-level shortstop when they look at Renteria, who's hitting the DL with a Grade II hamstring strain. He really hasn't been that since he was in Atlanta. Now 34, Renteria is seeing a lot of things change. As he tried to run out a bunt on Tuesday, his hamstring changed and it appears to be in a bad spot. Renteria grabbed at his hamstring, as is natural, but grabbed very high. The location of a muscle strain is important, because location influences function. The strength, thickness and ability to rest a muscle all changes with location. Usually, the thickest part (or belly) of the muscle is easiest to overcome. The top of the hamstring is often stressed because of imbalances in strength between the quads and the hamstring, and by the activation of the glutes during a sprint. Renteria will miss well into June with this one. The Giants are hoping Juan Uribe can play well enough to let Renteria buy some time to heal up.
For what it's worth, it did appear that Beltre grabbed a spot that was pretty high up his leg last night ... and Renteria ended up missing only three weeks. I don't know what that means, if anything, but I figured somebody else other than myself would find that interesting.