It is a sad tale. Jackie was always run first, just didn't prioritize WR, but he got a few good ones. Croom was just an idiot. He had several guys that should have been great, but instead of using them well, he tried to force them into his vision. Mullen really didn't care about throwing the ball, it was run, run, run. His offenses were even more run than Jackie's.
Hard for receivers to do enough unless they make crazy plays like Moulds did.
It also takes recruiting the right types for OT to make passing go.