I've had one in all my seasons of HD.
I don't remember the exact stats, but my guy played in (I think) 10 games in his injury season, then got another whole season from the medical redshirt.
Once I found out about the medical redshirt, I considered it a huge benefit he got hurt because he was FAR more useful the next season than in the one where he got hurt, and he helped guide the team to a deep postseason run.