Good teams get better in the clutch. I'm still not sure if the Chicago Bulls are a "good" team, but they do possess that knack for getting better down the stretch that good teams usually do. They're quickly developing a reputation of a team that's never out of a game, and a team that loves when it's tight down the stretch.
This season, the Bulls are 4-0 in clutch time games, and have the best net rating (plus-58.3) in those clutch time minutes. They look poised and not frazzled in the late stages of games, which is a great trait to have, especially with how many young guys are getting regular minutes.