During the 2006 Chicago Bears season, Grossman became the first Bears quarterback to start all sixteen games since Erik Kramer in 1995. In a season dubbed as a "roller coaster ride" by Grossman himself, the fourth-year quarterback had several productive performances, which were seemingly diluted by a handful of turnover-ridden games, especially in Week 6 against the Arizona Cardinals, where Grossman fumbled twice and threw four interceptions. While earning a passer rating of at least 100 in seven games, he earned a sub 50 rating in five games during the latter portion of the season. Grossman, who was recognized as the NFC Offensive Player of the Month in September, concluded the season's final month with a 64.4 passer rating, including a zero rating during the season’s finale game against the Packers. Grossman's work ethic drew criticism, when he admitted that he was not adequately prepared to play, and later claimed the game to be "meaningless." After noticing that his words had been misinterpreted, he rationalized his statement days later. His inconsistent performance drew criticism, and calls for Smith to bench Grossman in favor of the veteran Brian Griese.
Grossman's gunslinger attitude is illustrated in his desire to throw long passes, similar to his youth idol, Brett Favre. During the 2006 season, Grossman had an above average completion rate when throwing passes of twenty or more yards, but struggled to complete shorter passes. According to columnist Paul Attner of Sporting News, this attitude contributed to Grossman's inconsistent play. During Week 12 of the 2006 season, Grossman threw a game-ending interception while attempting a deep pass to Rashied Davis. However, during a Divisional Round game in the 2006 playoffs, he threw a 68-yard touchdown pass to Berrian on the opening play of the Bears’ second drive. Grossman commented on his non-conservative play style in a 2017 interview stating, "Coach Spurrier instilled in me, don’t check down if the big play’s there. So that’s kind of how I was born. I always wanted to shoot a three-pointer in basketball, hit a home run in baseball. I don’t know why, that’s just, like, who I am.”
The following is a list of Grossman's statistics from his regular and postseason games. Grossman has occasionally recorded notable statistics; among all quarterbacks during the 2006 season, Grossman ranked tenth in number of pass attempts, seventh in touchdowns thrown, and third in interceptions. He completed his first full season with a 73.9 quarterback rating. This was better than quarterback ratings of Favre, Peyton Manning, and Terry Bradshaw during their first full seasons; many other quarterbacks have performed similarly or better in their first years, including Grossman's former backup Brian Griese. His twenty-three touchdowns in one season rank Grossman among the best Bears quarterbacks in franchise history. However, his twenty interceptions in one season are among the most thrown by any Bears’ quarterback in almost two decades. The unusual combination ranked Grossman as statistically the most inconsistent quarterback in almost a decade in 2006. Grossman has the NFL record for worst passer rating in a victory with at least 15 passing attempts, recording a 1.3 rating in a 23-13 Chicago Bears win over the Minnesota Vikings on December 3, 2006. In the same year, Grossman became the first quarterback to throw more interceptions than completions in a game with more than 10 passing attempts.