re: Is Colt McCoy the best alltime Texas qb

Depends on how you define success.

Do you care about individual stats and direct contributions to team success?
If so, the answer is no. An Aggie provided a list of those that already trump Colt "if only he had played" McCoy

Or, do you value the business acumen of someone savvy enough to make a decade plus career as a professional backup to rake in the money taking far fewer hits?

If the latter, the answer is still no. The Detmer brothers have that title.

The brothers had a combined 22 years in the NFL (14- Ty, 8 - Koy) with only 32 starts and 157 games played between them. Ty got wise after starting the final 1999 regular season game for the Browns, in which he tore an Achilles. He sat out the 2000 season with injury and figured out starting was for the birds. When traded to the lions in 2001 where he somehow backed into the starting role, he managed only 4 starts. He led his "bench me, and pay me" campaign off that year with 7 picks in the first game (2nd highest single game mark in NFL history) just to send a message