He also wanted a linebacker instead of Emmitt. And just to note, the "3 rings" includes his Miami Hurricane title, not 3 Super Bowls, though of course college players have to be evaluated also.
Jimmy got 4 players and 6 first or second round picks for Walker. Don't have to be that great of an evaluator with that sudden influx of players in a short time, basically 8 players in two years, only have to hit on like 25% of the players to have a measurable impact.
He also had Norv Turner running the offense and Dave Wannstandt running the defense, a defense which was no. 1 in the league in one of the SB winning years.
Jimmy's main contribution was the atmosphere he cultivated, most everybody except the triplets and Haley were scared to death they'd be cut. And no salary cap to deal for the most part.
I dothink Jimmy was a very good coach but without the Walker trade bonanza I am not convinced he'd still have gotten the 3 rings, probably more like 1 or 2. Which would still be nice, but there's no way to tell how much of the 3 rings were due to his insighful player evaluations or just a wealth of players...