Carlson began his career as a backup to Warren Moon, and his most productive season was during the 1992 season due to Moon getting injured, when he passed for 1,710 yards in 11 games (6 starts). Overall, he posted a 10–4 record as a starter during his years as Moon's backup. Moon departed after the 1993 season with Carlson named as his starting replacement. However, he lasted only five games into the 1994 season, posting a 1–4 record and 44.7 completion percentage before he suffered an injury and missed the remainder of the year. Without his leadership the Oiler team continued to slump to a franchise worst 2-14 season. The coaching change in the middle of the 1994 season signaled a new direction for the Oilers, and, with Carlson coming off his injury, the team opted to let him go. He therefore retired after the 1994 NFL season.