Firstly, it was Thomas' rookie season, so regardless you'd have to give him more time.
Secondly, Thomas broke all of Colstons rookie records

Is it Thomas' fault that as per Payton's play calling, Thomas was not designated to run many deep routes. It was obvious Payton liked his ability to work the crossing patterns and break tackles so he got him working to his strengths.

Antonio Brown for instance didn't become the player he is now until his 4th year in the league.

Watch Michael Thomas in his rookie highlights completely out-muscle the DB's he faces and it's impossible to deny he looks like a special talent.