A new development may help explain why Chicago Bulls point guard Derrick Rose is still hesitant to return to the court. ESPN's Doris Burke spoke with the former MVP before Sunday's game against the Los Angeles Lakers and reported that although Rose has been taking full contact in practice for well over a month, his hamstrings are "on fire" after those workouts. Rose added that he won't return to the court until he's past those issues. A team source told ESPNChicago.com on Friday that one reason why Rose has been hesitant to play despite being medically cleared is because he still is struggling to dunk the same way off his surgically repaired left knee. For his part, Bulls coach Tom Thibodeau on Sunday repeated the same line he's used for several weeks now when asked about Rose's possible return this season. "We'll cross that bridge when we get there,"