There are many different ways to lead a group of men. There is no one-size-fits-all approach that is going to be effective in every environment to get a message across to every individual. Some will scream and shout and give the rah-rah speeches, while others lead by example, and those are just two of the many ways to be an effective leader.
Justin Fields is still just 25 and still very much growing as a player and leader, especially now that he is in a new organization with a much more established culture and way of doing things.