As Michael Crabtree inbounded the ball during an A.A.U. basketball game in north Texas three summers ago, Texas Tech Coach Bob Knight whispered to him the question that every coach wanted answered: “Football or basketball?” Back then, the question was not as easy to answer as it is today. Crabtree starred in both sports at David W. Carter High School in Dallas. He was a two-year starter at quarterback and the most valuable player of a state all-star basketball game in 2006. Colleges did not care which sport he played as long as he was on their campus. But as...