And it goes beyond the team-high six goals in nine games he has so far -- although that's a big part of the decision.
One of the words most often associated with Monahan when speaking with scouts and media members who met him in the run-up to the 2013 NHL Draft was maturity. While his birth certificate might read 19, Monahan doesn't act -- or play -- like a typical teenager.
SOG: 21 | +/-: -2
Physically, Monahan certainly is mature enough to play in the NHL. At 6-foot-2 and 185 pounds, he already has NHL-caliber size.
But the question always goes to the off-ice aspect of the game and life in the NHL. In that regard, it already seems like Monahan has matured into a solid aspect of the Flames' locker room.
"I have to admit that the entire team has done an unbelievable job with him," Flames coach Bob Hartley recently told NHL.com. "They like the kid. He's such a fine young man. There is absolutely no jealousy. I can see every day some veterans sitting down with him, helping him out, or even in practice or on the bench during games. It has been a total team effort and obviously Sean Monahan has been a very pleasant addition to our team since Day 1."
Hartley's role in Monahan's development also shouldn't be overlooked. He wisely limited Monahan's minutes in the youngster's first seven games, playing him an average of 14 minutes per game, and spotting him in high-leverage offensive situations.
But in the past two games Hartley took the reins off a bit and Monahan hasn't missed a beat. He played a season-high 21:11 in a 3-2 win against the Los Angeles Kings on Monday. He had a power-play goal in the second period, tied for the team lead with three shots on goal and played four of his six even-strength shifts in the third period head-to-head against Mike Richards' line -- and while on the ice his line did not allow a goal.
The next night he played 19:26 in a 4-2 loss to the Phoenix Coyotes. While he didn't get on the score sheet he managed two shots on goal and won 41 percent of his faceoffs. And he also played against the opposition's best players, getting multiple shifts in the third period against Antoine Vermette's line and Martin Hanzal's line.
If Monahan is responding well to an increased workload now, it certainly bodes well for his future and makes it more sensible for him to stay in the NHL.
The Flames' other option was sending him back to his junior team, but how would another season with the Ottawa 67s of the Ontario Hockey League help Monahan's NHL development?
It's only been nine games, but Monahan has proven he can play at the NHL level. While his next nine games might not go as well as the first nine, the experience he'll gain will be invaluable as he continues what looks right now to be the start of a very solid NHL career.