I had this thought, but the Eagles played 10ish games there a year including postseason and preseason as opposed to 81.
I'm not sure this stuff is statistically significant. It would show up in other astroturfs, right? And three times the national average in such a small sample? Well I wouldn't jump to conclusions on that. Other possible causes I'd want ruled out: chewing tobacco, steroids/ped's/supplements, some chemical plant upwind from Veteran's field during the summers, etc...