re: Who are the best professional players in the NFL, NBA or MLB that were not very good in c

Rayfield Wright played several positions at a small college, was a late round draft choice, and didn't see the field for his first couple of years as a pro.

The Cowboys moved him to Tackle out of necessity and he ended up making the 70's All Decade team and was eventually inducted to the HOF.

Not sure he counts because he never played Tackle in college.