The 6-foot-6, 231-pound native of Macomb, Mich., had 68 points (28 goals, 40 assists) in 56 games during his final junior season in 2014-15, when he helped lead Oshawa of the Ontario Hockey League win a Memorial Cup title after a midseason trade from London.
"I think it was a huge step for me just being able to be around an NHL locker room," McCarron said. "Those 20 games when I was up here, I was able to see people's bodies and just know that I have to get there to continue to play well and maintain throughout the whole season, and where I was last year wasn't going to cut it.
"And obviously it didn't cut it. I was sent back down to the minors, and I just got that extra boost to continue to work on my body. And like you hear these guys say, I wasn't going to be playing in the NHL at 18. It was going to be a process and things needed to change and I just continued to work hard."
McCarron demonstrated his battle level during development camp when he crossed paths with Montreal's most recent top draft pick, 18-year-old defenseman Mikhail Sergachev, selected No. 9 by the Canadiens in the 2016 draft.
"[We had] been going at each other for a couple of days and he said something and I said something, and we both disagreed on it," McCarron said. "We're battling for a spot and we're both competitive players, and it wasn't just us who were going at it, there were other players who were getting a bit heated, and even in summer league you're still really competitive and you want to win, even if there's nothing on the line, just pride, and we were just battling and he took it well. You know what, he's a tough kid, he's a big kid, and I thought it was good for us."