Belichick's story is pretty well known. He failed massively in Cleveland and it led to his firing after five seasons, despite an 11-5 season in 1994.
Rivera got off to a slow start in Carolina and was on the hot seat several times throughout his tenure with Carolina.
Look at them now!
In order to truly judge an NFL head coach you need to give them a good amount of years to see the roster change.
Jason Garrett inherited a terrible situation when he became the head coach of the Dallas Cowboys. It was a top-heavy team with tons of money tied up to aging players.
At a point in 2010, the average age of Dallas Cowboys starters was 29 years old. To open 2015, the average age of the Dallas Cowboys was 26, three years younger and considering they have a 36-year-old quarterback and a 33-year-old tight end.
Garrett has completely overhauled the Cowboys roster and has done so committing to young players. The Cowboys have invested premium picks on offensive line talent, something contradictory to the traditional splash drafting the Cowboys have exhibited in the past.
The fact of the matter is that this team is trending upward and had it not been for key injuries, 2015 would not have been a bump in the road.
People like to argue about the three 8-8 seasons to start Garrett's coaching career. I find that more impressive than anything. To overhaul a roster like Garrett did while staying playoff relevant is a plus, not a minus. Keep in mind, Garrett had no head coaching experience prior to the Cowboys.
The players absolutely buy into what Garrett tells them. Watch these players speak in interviews and they sound like Garrett's robots. You will hear the traditional phrases Garrett likes to use, like the process, one game at a time, etc.
The way Garrett motivates these players is inspiring. Watch any video on the Cowboys website where Garrett is speaking or motivating his players. For instance, the video where Garrett takes his players to visit the World Trade Center will give you chills.
This is a Princeton graduate who speaks with poise and is never rattled. He understands the sport and more importantly knows how to handle human beings. It isn't about splash with Jason Garrett, it is about getting good players and winning football games.
Can Garrett improve as a coach? Absolutely he can. I would like to see the staff as a whole become less stubborn. Sometimes there is something brewing and the team is hesitant to make the move. For instance, Lucky Whitehead as a returner was clearly more dynamic than Cole Beasley, yet Garrett was hesitant to create change. Keeping with Lucky Whitehead, instead of making him a gadget player, they should be creative and use him as an actual wide receiver.
Making the change to Kellen Moore, deploying the young players late in the season, etc. are some decisions I wish Garrett had made easier and quicker. We never got to see Chaz Green or Damien Wilson when it would have been useful for them to get some experience.
Garrett tends to be hesitant to create change, but sometimes it is necessary.
At the end of the day I'm ready to let Jason Garrett handle the Dallas Cowboys for the long haul. Let's see this man make his mark on the Cowboys roster. Give him complete control to decide who he wants and who he doesn't want anywhere near his locker room.
The chemistry the 2014 Dallas Cowboys had was something I have never seen in 23 years of fanhood. That team went to war for each other every single week and seemed to love playing and being together. You could see how hard they played on the field. The defense didn't have many standout players, but you saw them give their all on every single snap and it made all the difference.
Let Jason Garrett build a TEAM. He understands what it takes to have 53 men coming together to win football games. He understands it doesn't matter what position you are, where you come from, the pedigree, what you have done in the past…it matters what you can bring to the Dallas Cowboys and add to the team as one of 53 players.
There will be bumps along the road, but Jason Garrett is the right man to lead the Dallas Cowboys.