Fish-Head really hit the nail on the head. To add a little detail to his wisdom ... here goes.
Shula was a run-first guy, he built his teams to dominate in the run game ... and he had a Hall of Fame QB named Bob Griese and a Hall of Fame WR named Paul Warfield, so he adapted his game style to accomodate a relatively balanced approach with a strong passing game too. But, he built his team around the best FB ever to play the game, Hall of Famer Larry Csonka. He had a great OLine too. But, picking out talent wasn't all that developed back th en. To give you an idea, here are some of the guys who were assistant coaches or GM's under Shula ... and you quickly see he had an eye for all types of talent: Howard Schnellenberger later of the University of Miami and Louisville fame, Bobby Bethard who later built the Redskins Hogs/Gibbs dynasty, Bill Arnsparger the legendary defensive coordinator, and there are many many more exceptional guys who worked under and learned from Shula.
So when his QB was poor, he reverted to a dominant running attack with dink and dunk passes. Then he molded the team around a running QB named Woodley who surprised everyone by being fairly effective. Then Dan Marino fell into his lap, and he retooled the team again into a dominant passing team. That's just the offense.
On defense he had the undefeated season's defense known as the "no name defense" because it had lots of very good players but didn't have one real dominant player. Later he did a similar build with the Killer B's of Betters, Bokamper, Baumhower, etc.
Just about every great coach is known for having a style that they hardly ever veer away from ... think about it. Walsh designed the West Coast Offense. Chuck Noll played power running and dominant steel curtain defense. Jimmy Johnson was bigger and stronger than everyone else on both sides of the ball. Parcells always plays power offense and a 34 pass rushing defense. Etc., etc., etc.
But Shula is probably the only legendary coach who actually adapted his style to his personnel effectively. Every other coach just kept feeding his own system with players that fit, never breaking the mold. But Shula was able to win year after year after year despite drafting low just about every year ... because he took what he could find and adapted the team to those players instead of forcing rebuilding years as he acquired players to fit his system.
Shula was a disciplinarian but not the same as some of the intimidators before and after him. He was a detail oriented guy who almost always had one of the least penalized teams in the league. It was no accident that 100% of his players on the punt coverage team knew to give Leon Lett just enough room to touch the ball, and then pounce on it ... because Shula's players were always extremely well prepared and knew exactly what to do in every situation. He would stand for no less. The great players were allowed to be great, and the role players put the great players in position to make plays. Everyone else made sure not to make any mistakes, lol.
Shula didn't overprotect his defense at the expense of his offence. In fact, he was always a very powerful offensive team. He used disciplined defending to keep the other team from scoring too many, and to generate take-aways, and then he just went out there and dominated the other team with his devestating offenses. Sometimes it was the unstoppable freight train of Larry Csonka, or lesser players in similar roles like Andra Franklin or Keith Byars, and other times it was speed backs like the stellar Mercury Morris, or the short-lived David Overstreet, and other times it was just lesser athletic talents with enough savvy to get the job done like Tony Nathan. Sometimes it was speed receivers like Paul Warfield or Mark Duper, other times it was open field masters like Mark Clayton or Nat Moore. He was successful with weak-armed dink and dunk masters like the lovable Don Strock, gifted QB's like Bob Griese, or backup QB's like Earl Morral, pocket passers and scramblers like David Woodley and when he had a gem like Dan Marino, the record books were all re-written with his name, signed in the ink of Shula's tremendously adaptive offensive schemes. The perfect season he had a physical run-blocking line, during Marino's reign he had a finesse pass-blocking line, but whatever best suited his personnel, that's exactly what Shula's teams became.
Don Shula truly was the best at everything as a coach ... and on top of all that, he was a hell of a likeable and respectable man. And .... an unquestioned winner. Honestly, I couldn't possibly be more impressed with Don Shula the coach or the man.