Sample: All BYU years post-LaVell starting at BYU

PR(BYU Player Drafted = 1) = B0 + B1 Mendenhall + B2 Crowton + Controls

Controls: Player age, recruiting ranking, number of rounds in the draft during that year, player position, anything else that you can think of...

I bet that you could throw a million controls in this model and B1 would always be negative and significant.