What?
If he can be a 90 on the Pats that means:
He's not "done" and is just playing behind a bad line.
or
He's not that good but the Pats somehow could get elite production out of him.
If it's the first choice - why does he need to be dropped? If it's the second choice, then go ahead and drop him, but take into account that no team can get elite production from a true scrub.
Before killing LDTs rating, make sure he's actually HIMSELF ineffective. If he is - that's fine, drop him. Don't slam him because he's got a bad line. Slam the bad line.
It's not about "not understanding Madden." The GAME won't take a 79 and make him another rating because he got traded, so why should any roster creator do that, Donny or anyone else? That doesn't make sense.
If he goes to a better running team, then the line and run plays should make that happen, not somehow magically add 11 points (if he "should be" a 79) to him.