There is a huge difference between cheerleaders and motivators. Cheerleaders are usually guys that don't have much of an impact and motivators are guys that lead by example or can be vocal like Micheal Irvin and other guys like one of my favorites of all time Jack Lambert who was outright mean! You know who used to be mean on the Cowboys, Erik Williams, I loved that guy's attitude!
Michael Irvin's motivation didn't become relevant until Jimmy Johnson came. He was awashed in a locker room of no-talented guys and a coach whose schemes had passed their time.
Eventually, Irvin would have become frustrated unless he had a coach who installed a scheme that could work. Then, his natural leadership qualities made themselves known.
Same with Jack Lambert who played for the greatest assembling of talent on one team in NFL history. He had a coach who knew how to get the team to work together. Thus, his motivation skills were enhanced.
It all starts with coaching, scheme and talent.