Looks like something went odd with the punt game. Every single punt in my game went over the returners' heads with no attempt to return it.
If the ball will land within the 10 yard line there is a decreasing probability that the returner will attempt to field it, were the punts in question close to the end zone or were they outside of the 10 or 20 yard line?
You know what, you're right, I just checked some punts and the returner is not fielding them. I think the changes I made to the coverage team has broken that, I'll try to get it fixed before the season opener.