Canadian football is a pretty rare game.. and AC is a rare example of a QB having essentially mastered the game.
There are 8 pro teams playing this variant of football and the 3 down variant is only consistently prevalent nationwide at the CIS level and up. You can chalk up 20 development programs and 8 pro clubs. That's pretty much it. Even at that, the best raw talent comes from football factories in the states playing the very different American variety of the game...
It takes time (years) to learn the nuances of this game, especially at QB.
How many QBs has BC, Calgary, Saskatchewan, Winnipeg, Toronto and Hamilton gone through in the last 10 years?
Its one tall task to truly be a student of the QB position in Canadian football and excel at it for so long.
The Canadian game is pure muscle memory for AC and many of his receivers. He's had so much time to sharpen his tools and has luckily avoided serious injury over his decade in Montreal.
When did Calvillo take over from Tracy Ham? 2000? Calvillo himself laboured for 6 seasons with Las Vegas, Hamilton and as a backup in Montreal before he was signal calling in a Grey Cup game.
See the following which pretty much sums up Calvillo's time in Vegas and Hamilton:
(Also for those who think the Argos are worse off today than in the 90s.. take note of the Toronto crowd in 1994)
What's more, he's now done it with success for 10 years and been to 7 Grey Cups. I mean yeah, Marcus Crandel won a Grey Cup with an 8-10 team but where was he a few short years later?