While he's easy to miss in stature and statistics, St. Denis is impossible to overlook with his burgeoning responsibility on the ice.
"He's kind of our hidden gem. He's the man," Bulldogs coach Guy Boucher puts it. "He can do so much. That's the thing about St. Denis. Whatever you need, he's got."
During the regular season, that meant becoming a versatile and quick study on a defense whose 182 goals allowed were the fewest in the AHL.
Yannick Weber injured and P.K. Subban recalled to Montreal.
Whatever anonymity helped St. Denis grow into his greater responsibility to this point has been ripped away. As Hamilton battles Abbotsford in the North Division finals, St. Denis' playing time has been boosted and he's become one of the irreplaceable standard-bearers of his unit.
"We have to cover P.K's ice time. I see it as a challenge for me, not pressure," said St. Denis, 24. "When they approach me to play more, I just take it. The coach puts me on ice in every situation. I just want to go on the ice and show what I can do."
The problem for much of St. Denis' career is that his skill set has been a little murky. He could help out offensively a bit -- he went 17-50 during one of his years with Drummondville of the QMJHL and was 1-22 for Cincinnati of the ECHL last season.
That was all fine, but not quite flashy enough to mark him as an elite offensive defenseman. And, at 5-foot-11, 190 pounds, he was no one's vision of a defensive bulldozer.
"You know how it is with defensemen," Boucher said. "If they are not big, they better be extremely skilled. That wasn't the case with him."
St. Denis didn't get any free-agent offers he liked coming out of juniors two seasons ago, so he went the college route at the University of Quebec. The hockey education was profound. He put on some weight and incorporated a lot of game sense.
Hamilton was impressed enough with the metamorphosis to offer him a two-year AHL deal. He got just seven games in Hamilton last season but continued his graduate work in Cincinnati, where he was a gaudy plus-28.
"It was good for me to see professional life, what it takes to be a professional, have some ice time, too," St. Denis said. "If I was in Hamilton, I don't play. That was a benefit for me to play in Cincinnati."
That wasn't readily apparent in Hamilton when St. Denis was pegged as an extra to start the season. But when Mathieu Carle went down with a shoulder injury in January, St. Denis became a regular for a team that would run away with the North Division on the back of its defensive unit first and foremost. He went 3-14 in 59 games but those efforts were just a side dish to his minutes-eating consistency and a plus-20.
"My first idea at the beginning of the season was not to get scored on when I was on the ice," he said. "I tried to do good in my zone. I tried to focus on my one-on-one battles. We have some good defensive players this year who taught me how to play defensively. That helped me a lot during the season."
St. Denis needed all the tutoring available to cram for what he described as Boucher's complex system.
"It's passive aggressive. We want to wait in the neutral zone. We focus a lot on stick on puck, trying to do some turnovers in the neutral zone," he said. "If everybody can do his role in the system, it's tough on the other team. When we play against skill guys, it's tough for skill guys to go into the zone with the puck. For sure, this year we (ticked) some guys off."
St. Denis' biggest ally was the man who controlled his minutes. Boucher coached him for one year in Drummondville and saw St. Denis' poise and activeness as perfect fits for his demands.
"We can spot him in any position. He fits in to where he is because he is a real two-way defenseman," Boucher said. "When there is chaos out there, you want him out there because he doesn't give the puck away. He's really a great puck manager. And he's a little nuts in the sense he'll block any shot."
"We can spot him in any position. He fits in to where he is because he is a real two-way defenseman. When there is chaos out there, you want him out there because he doesn't give the puck away. He's really a great puck manager. And he's a little nuts in the sense he'll block any shot." -- Guy Boucher
"It's not a good show for the fans. But during the season, it's good for us," he said. "Actually, it's the first time I can say I'm part of a good team like that, (with) great defensive players. It's really fun for me."
And there will be smiles all around in Hamilton if St. Denis' continued improvement helps the Bulldogs to the same success the next few weeks as they turned in from October to April.
"We had a pretty good run this season," St. Denis said. "We want to continue that way for the playoffs. Defense wins championships. I think the system can work against any team in the league."