It would be nice if Tom could play at a fairly high level till 45. Right now it isn't looking like that will happen. I know it isn't just him, but Tom has made it work before with substandard cast. He can't do it anymore.
This offensive scheme has a big weakness to go along with it's big strength. That being (provided you get players who can run it) you need guys who can win 1 on 1 by sustaining and hopefully increasing mild advantages.
Designed plays are set up to get a single player space and then have dump off options. This offense is more designed to get the angle based off what the DB is doing pre-snap and beating him to the spot. If you are facing more talented players across the board get that minor advantage means very little. They will still beat you to the spot.
If that is the case you're better off with designed play calls to get someone open. Sadly we are short on those kind of plays.