The problem seems to be that VC overcorrected something that occurred in 2K4...... KR/
PR were too easy. If you watch the replays and take a look at your defenders you can see that for a short time they act as if they are spectators on the play and not actually involved. Sure you can juke and jive your way down the field in an unrealistic fashion, but it sounds like you don't want to have to do something that makes it look like your guy is having a seizure on his way into the end zone.
One solution I came up with, though it is not perfect, is to replace on the kicking and punting teams (for both you and the cpu) the attackers with the slowest guys on the team (O-linemen, TE's, backup QB's, etc.). It takes a little time and a little doing at first, but I think you'll like the results both ways....the cpu also makes better returns and can even be a threat to take one to the house. Also, when you are kicking or punting to the cpu, don't take manual control of another defender.... just let the controller go and let it play out. Your kicker will run down automatically and get involved in the play.
Oh, and here's a tip if you really want to try this...... when you shuffle back and forth to substitute in the "slow butts" you don't have to pay attention to the names. The game will automatically sub in the backups and someone who is not already on the list. For example, say you are bringing in all of the backup offensive tackles in the stable of 5 that you have (so 3 will be on the kicking / punting teams; the game will not put the starters in). You choose the existing slot for who you want to sub, go to the tackles, pick the 1st tackle there who is listed (even if he is a starting tackle) and the game will stick in one of the 3 backups. You can then repeat the process for 2 more slots and get all 3 backup tackles on the coverage/attacking kicking team. It's a bit more convenient that way and saves a little time.