Sure you can argue that the fact that Derrick Rose has matured into a all-star and the signing of Carlos Boozer had a bigger impact, but Thibodeau and his defensive coaching scheme is what has kept the team on track.
Even without Boozer for the start of the season and Joakim Noah missing almost half the season, Thibs has found a way to keep Chicago winning.
The Bulls defense ranks among the best in the league and their ability to force opponents to shoot bad shots has made Chicago one of the best rebounding teams in the NBA.
Chicago's offense often relies on D-Rose being able to make a shot. Although No. 1 most of the time delivers, when he doesn't, the team stays in the game thanks to it's shot defense. This gives the Bulls an advantage that few teams possess and now Chicago is just two games behind from the first-place in the East.
Something like that wouldn't have happen without the arrival of Tom Thibodeau. Thibodeau came to town with low expectations by critics and fans alike, but now he has raised the bar for how the team should play.