McCoy was a midseason replacement for Calgary in August 1999 after Dave Dickenson and Henry Burris suffered injuries. He learned on the run, completing 117 of 183 passes (64 percent) for 1,669 yards, 10 touchdowns and just two interceptions.
According to his college head coach at the University of Utah, Ron McBride, McCoy learned Calgary's entire playbook in a day.
"That's his whole thing -- he's intelligent," McBride said. "He doesn't get rattled. He's confident. He knows what to do. Pressure doesn't bother him. He's the same way coaching. He doesn't get rattled. He has the same demeanor throughout the game."
McCoy led Calgary to the Grey Cup as an injury replacement, losing to Hamilton 32-21. Calgary wanted him back the following season, but at 28 years old, McCoy was ready to relinquish his dream of playing professional football.
Former San Francisco head coach George Seifert had taken a new job as head coach of the Carolina Panthers, offering McCoy a chance to work as an offensive assistant and quarterbacks coach for offensive coordinator Bill Musgrave.
"This was an opportunity of a lifetime," McCoy said. "I had always thought about it, and people had always talked to me about coaching. But to make that jump at such a young age and to work for a great coach like George Seifert and Jerry Richardson, as an owner, I couldn't pass it up."
McCoy quickly switched over to pursuing another dream -- becoming a head coach in the NFL.
Fast forward 14 years later and McCoy has reached his goal. One of eight new head coaches hired in 2013, McCoy is the only one still left in the postseason. That impressive fact is a testament to living up to his word when he first addressed the Chargers after being hired on Jan. 15, 2013.
On his way out the door after being relieved of his head-coaching duties, Norv Turner said San Diego had some serious work to do to once again become a playoff contender. But McCoy proved Turner wrong, leading the Chargers to the playoffs just a year later.
"From the very beginning in the first meeting, it was about us," safety Eric Weddle said. "It's not rebuilding. We're going to do things right, on and off the field. You're going to be a good person, and it's going to transfer over. And the ultimate goal is to win a Super Bowl.
"From the onset, that's what it's all been -- being confident and believing in each other. Every day he's preached it, consistency and belief, belief, belief -- that we can go in, play with anyone and beat anyone. And when you hear it every day, and the older guys transfer it down and push this team in the right direction, you're capable of doing anything."
McCoy, 41, instituted a dress code for game days, making players wear a suit and tie on road trips, giving birth to Philip Rivers' bolo ties. McCoy's a task master, paying attention to every detail of this team's schedule from sunup to sundown.
McCoy has a tough, no-nonsense attitude. He can be a bit paranoid about injury situations regarding his players, divulging as little information as possible on the status of his star performers heading into a game day.
But he also has built a bond and a trust with the Chargers by showing he cares about them. And that nurturing attitude stems from McCoy's time as a fringe player in the NFL and a star player at the University of Utah.
McCoy went to training camp with Denver in 1995, signing with Green Bay's practice squad that year. He played for NFL Europe's Amsterdam Admirals, and also spent time in San Francisco and Philadelphia before concluding his career with Calgary in 1999.
In college, McCoy led the Utes to a 10-win season and a 1994 Freedom Bowl victory over the University of Arizona's "Desert Swarm" defense.
"Being a former player you can always relate back to the players," McCoy said. "That is one thing that helps me now. I was very fortunate to only have one injury and it was in college. You see the ups and downs, and the losses you take at certain times that are harder than others."
San Diego's success did not come early. The Chargers hit a season-low at 5-7 during the 2013 campaign, but tight end Antonio Gates said players finally started to believe in McCoy's philosophy and approach.
That belief, along with key players such as King Dunlap, Jarret Johnson and Melvin Ingram returning to the field, resulted in a five-game winning streak -- and the Chargers being eight quarters away from the Super Bowl.
"Mike is very detailed, and very understanding," Gates said. "I can't say enough about what he brings to this team. The leadership ability that he has, and the ability to keep us poised in tough times, to me all those messages he tried to put out, unfortunately it took time for us to comprehend and buy in. And now we're just at a point where that's happening for us offensively and defensively as a group."