He is VERY selective in giving second chances because he knows that if he gambles on the wrong player it could seriously hurt his program AND make it hard to give others a second chance.
There are a lot of articles about this, here is an AP article:
http://www.usatoday.com/sports/college/football/2007-10-31-2786717246_x.htm
I don't remember a single mistake that JJ made on players at UH. Here are the key players JJ gave second chances too:
Pisa Tinoisamoa: One of JJ's first recruits at UH, this LB spent 4 months in prison during his senior year of high school! The LB it seems that JJ is giving a second chance to at SMU didn't have anything that serious on his record! JJ did his homework carefully about Pisa (it helped that Pisa is from San Diego and JJ was the head coach of the Chargers when the Pisa got into trouble) and took a lot of criticism when Pisa came to UH. How did that work out? Team MVP. All-America 3rd team. All-Conference. 2nd round draft pick. Played 5 seasons in the NFL so far and the Rams gave him a long-term contract extension. No off the field problem in college and the NFL.
Colt Brennan: Discarded by Colorado in 2003 after he entered a woman's room (he says he was invited) while drunk and not leaving right away. Rape charges scared everyone off but witnesses said that Colt never touched her...he was convicted of burglary (entering the room) and trespassing (not leaving right away). How did that work out? Role model for the entire state, including speaking to every school, juvenile detention facility, and troubled kids program. Heisman finalist. All-American. 5,549 yards, 58 touchdowns in 2006 (not bad for a guy who was a walk-on in 2005). First outright conference title. About to be drafted by the NFL. No off the field problem in college.
Davone Bess: A month after he graduated from Skyline High School in Oakland, Bess was arrested after allowing friends to put stolen property in his car. He says that he had no idea that those things were stolen, but refused to rat out his friends so he lost his scholarhip offers and was sent to a juvenile detention facility for 15 months. The tape that JJ watched of him was from a pickup football game while he was incarcerated! How did that work out? All-American. About to be drafted by the NFL. 3 seasons with about 100 catches per year and about 1200 yards per year with about 14 TDs per year. Soon to be drafted by the NFL (he left early after JJ went to SMU). No off the field problem in college.