Ok the good news: the injury bug is NOT something that will happen during every career. What triggers it? Josh and Team HC will look into that Monday. I started a new career and the injuries worked fine. So hopefully EA can get this fixed bug in the meantime just keep an eye on your injured players to see if they're healing properly.
In testing this injury bug I was able to sim a season and get a look at the stats. For the most part, it looked fairly good. I basically just looked at the leaders in various categories but it wasn't too crazy. Reggie Wayne nabbing 2,100 yards receiving was a tad extreme. Wayne destroyed Rice's single season mark of 1,848. Manning also flirted with Marino's single season yards record, but failed by 35 yards.
I think there were eight 4,000+ yards QBs, only 11 1,000 yard rushers, and Tom Brady led the league in completion percentage with 65%. There were a lot of QBs with 40+ TDs, though. By a lot I mean maybe four or five. That's pretty high considering throwing 40 TDs has been done only five times in NFL history. I think Manning had 45 TDs and 24 INTs.
So, will the sim engine blow you away with its amazing and uncanny accuracy? Probably not. Granted, the one season sample size is pretty pointless to judge the engine by..but hey.
More importantly: is it good enough? That's a question you'll need to answer for yourself.