The great debate is what do you need for your team to be successful? Do you need the players coach that can pat you on the back or do you need a guy who will yank your face-mask hard enough that would get players ejected? Both have led to multiple titles, but which one is easier and more productive.
Players coaches: Players love to play for these guys, but results seem to be limited. It works if they can come in and have success early on in the coaching tenure, but if failure happens early it seems like the players stop playing for these guys. Look at the Bucs when they had Dungy, they could always get to the Divisional round, but could never make a strong title push. When Dungy was dumped for Gruden, the players responded and won the title. Dungy went on to have the same success with Indy, but it took many more years before he broke the barrier. Amazingly both coaches exited this year but on completely different ends. Dungy was able to retire with respect and Gruden was given a dis-honorable discharge from the Bucs.
Drill sergeant coaches: These guys are only liked when results are shown and once they win a championship they normally get too settled in and too satisfied with their accomplishments that their fire and will to win runs out. A year or two after they win a championship they should move on to another team. These guys are all about setting goals and once they are reach there is nothing else for them to do. Again look back at Gruden. He came, he won, he settled. The same thing can be made about Cowher. He wanted a superbowl victory and got it, he didn't repeat so he left. Parcells is the best example of all. These coaches can turn one place around but once they win thats it. If they do it quickly there is no reason to stay. Turning a 4-12 team into a superbowl team is accomplishment, but taking that team to just to anything less the year after normally marks the end for the coaches tenure.
Players coaches are always going to be players coaches. They can try to be tougher on guys because it's not their nature. What you see is what you get.
Drill sergeants on the other hand can always back off. This normally shows acceptance to players. Players feel like they have bonded to this coach almost like a son. Do you think Brady will ever play for anyone else now that he has been with Belichick. No he is his kind of guy he sees the coaches' acceptance and is very comfortable in his situation.
What is the better method?
While neither method is perfect and I do think a team will have more success by always switching from one back to the other I perfer the get in your face style coaches. Reasoning, they simply produce more. 6 of the last 8 superbowls were won by coaches who don't put up with players that think they are bigger than the team. Coincidence, not at all. Look through-out the history of the game. Lombardi, Landry, Shula, Noll, Walsh, Parcells, Johnson, Belichick---all multiple superbowl winners, all coaches that don't put up with players above the team.