Kubes waived Holiday apparently because he didn't have the patience to wait to see if he matures in the job and can be trusted to make good decisions & not fumble.
The Broncos on the other hand were kind of desperate for a return guy. We had Jim Leonard, and Decker in a pinch, and that is it. Fox wisely put Leonard in on the high pressure kicks, and that allowed Holiday to get comfortable and gain confidence. Slowly, but surely, Holiday earned more and more of the coaching staff's trust.
The rest is NFL history.