Croyle played quarterback for the University of Alabama football team from 2001 to 2006. He was a highly regarded prospect coming out of Westbrook Christian High School, and was recruited by various college football powerhouses such as LSU and Florida State. On the night before he was to announce his college decision to attend Florida State, Croyle changed his mind and decided to play for Alabama. He enrolled as a student at Alabama in January 2001 - a decision which proved to pay off. He beat almost all of the Alabama passing records despite his injuries. His numbers beat out some of the All-Time greats records such as Joe Namath, Mike Shula, Bart Starr, and Ken Stabler. He also got to experience a throw to Tyrone Prothro during the second quarter of the Alabama-Southern Miss game that won Alabama the Pontiac Game Changing Performance of the Year.

In 2001, Croyle redshirted and therefore did not play. In 2002, he was the backup for senior starter Tyler Watts. After the 2002 season, Alabama head coach Dennis Franchione resigned to take the position of head coach at Texas A&M. Washington State head coach Mike Price was hired to replace Franchione in January 2003. Coach Price coached Croyle throughout the 2003 spring drills and practice, but Price was dismissed from the head coach position in May 2003 for off the field transgressions. Soon after, Mike Shula, quarterback coach for the Miami Dolphins, former offensive coordinator for the Tampa Bay Buccaneers and former Alabama quarterback, was named head coach at Alabama. Croyle had only a few weeks to prepare and practice under rookie coach Mike Shula's system. Neither Croyle nor the Alabama football team were productive in 2003. Croyle's play was hampered by a midseason shoulder injury and the team finished with a 4-9 record, including an 0-6 record in games decided by one score or less.

Croyle started the 2004 season with a lot of promise, but during the third game of the season against Western Carolina University, Croyle tore his anterior cruciate ligament. Croyle was forced to sit out the rest of the season, and the team finished with a 6-6 record. Croyle returned fully recovered in 2005 and passed for 2,499 yards, leading the team to a 10-2 record and a victory over Texas Tech in the Cotton Bowl.

On April 29, 2006, the Kansas City Chiefs drafted Croyle in the third round of the 2006 NFL Draft. Croyle saw few snaps his rookie season and played in only 2 games. His passer rating was 11.9, having completed only 3 of 7 passes for 23 yards including 2 interceptions. On March 27, 2007, Chiefs head coach Herm Edwards indicated that he is leaning toward starting Croyle in 2007.