The Bengals were already being led by an established NFL star, Norman "Boomer" Esiason — the 1988 NFL MVP — who like Wilhelm threw the ball left-handed. Adding a left-handed backup in Wilhelm allowed the Bengals not only additional depth, but the luxury of leaving offensive line protections unchanged should Wilhelm enter the game, with the right tackle rather than the left tackle being responsible for the critical task of blindside protection on passing plays. Initially wearing the number 12, Wilhelm saw limited action backing up Esiason in 6 games during his 1989 rookie season, completing 30 of his 56 passes for 4 touchdowns, at a cost of 2 interceptions.