At his lowest point, Trestman, on the advice of a mutual friend, sought the counsel of Gary Stevenson. The longtime sports television executive was known as a man who could give good advice.
Trestman told his story to Stevenson, who now heads up Pac-12 Enterprises. But where Trestman saw a dead end, Stevenson saw one road branching out into many others. Trestman just had to pick one.
He urged Trestman to look at this period, during which Trestman still was being paid by North Carolina State, as a time of liberation. He pointed out most successful people have the best runs of their careers between the ages of 45 and 60.
Really, what Stevenson did was remind him that the keys to Trestman's shackles and chains were right there in his pocket.
Trestman started to look at his firing as an opportunity, and this period as the halftime of his working life. And he had plenty of time to re-evaluate the first half while game planning for the second.
He read books on leadership. He centered himself. He retraced the steps of his career.
When he looked back, this is what he saw: An unfulfilled, unhappy man with a "standoffish personality." Even his wife Cindy lovingly referred to him as socially dysfunctional.
Trestman was one of those coaches who would close his office door, turn off the lights, turn on the tape and grind. That's what coaches do, right?
Trestman was so caught up in X's and O's, he forgot the game was about people.
"I was never belligerent, malicious or mean-spirited in anything I did," he said. "I was just not paying attention very well to what was going on around me. I was so focused on my work that I didn't recognize it's more important to develop ongoing relationships with people, to spend time with them, to get to know them, to let them know that you care."
He thought back about his father Jerry, who had owned a restaurant called Danny's on 14th and Chicago in downtown Minneapolis. Employees had been loyal to him for nearly three decades.
"I realized why people loved my dad so much," Trestman said. "He cared about people. That's why they worked so hard for him, that's why they chose to stay there. I decided it was time to look at the way I did things differently."
He also flew to Los Angeles to spend time with his old pal Pete Carroll. Back in the day, they were the whiz kids on Grant's Vikings staff — "Bud's Boys," they were called.
More than 20 years later, Carroll was the most successful coach in college football at USC, and Trestman was nowhere.
Trestman watched how Carroll coached his players and built his football philosophy — how the Trojans organized practice, what they emphasized and how their week was structured. Carroll mapped it all out for him.
Now, Trestman had a blueprint. And so he came to a decision.
"I was 50," he said. "I crossed this line. There was not much time left. You feel mortality. I didn't want to be a coordinator again. I needed to be a head football coach."
These days, there is a calmness about Trestman that can emanate only from inner peace.
He doesn't just look you in the eye. He looks through your eyes, as if he is searching for something beyond. And he shakes your hand with a big, powerful, thoughtful grip.