Bickerstaff has no hesitation pointing to the reason for the long playoff drought: He couldn’t prevent Mutombo from leaving in free agency in 1996. “My biggest regret, no doubt about it,’’ Bickerstaff said. “It got down to money. He wanted to stay, his agent was working with us, but we couldn’t make it happen. Losing him was the beginning of our demise.’’ Mutombo was headed to Atlanta, where he and his right index finger would forge the next iconic images.