"He's a kid that's calm beyond his years," Maple Leafs teammate Cody Franson said. "He comes to the bench joking around, just all happy and go-lucky. I sat there and said to Orrsy, 'You remember being that calm when you were that age, playing junior?' "
Junior hockey for Franson was seven years ago and for Colton Orr it was more than a decade ago. For Rielly it was last year.
Yet now Rielly is a veteran of 40 NHL games and on Wednesday night scored his first home goal at Air Canada Centre in Toronto. The goal was a prime example of the 19-year-old defenceman's sublime instincts, and his rookie season has been a testament to his readiness at the professional level.
"I wish I was that good at 20 or 19," veteran Tim Gleason said. "I wish I was like him when I was that age. I was the total opposite. I was a nervous wreck every game and hoping to stay and not be sent down the next day. That was me, and he is who he is."
Rielly has been solid for the Leafs, dressing 18 straight games since a brief stretch as a healthy scratch in early December. But that doesn't necessarily mean his progression has been linear or followed a straight path.
"He's a young player that has taken some steps and then has taken a few sideways," coach Randy Carlyle said. "He's had his strong nights, and then he got sick here and I didn't think he played very well when he came back."
Carlyle lumped Rielly in with 23-year-old defenceman Jake Gardiner, who has now played 134 NHL games. But Gardiner has seemingly been in his coach's dog house more than Rielly.
"Jake's had some struggles with the puck, turnovers and we made a decision not to play him based upon he was making too many of them," Carlyle said. "And then when he came back in, it was the best game he played of the year. Where Morgan, we haven't taken him out of the lineup in a while and we feel that he's progressing."
The standards also aren't the same.
"Our expectations for Morgan aren't as high as they are for Jake at this point, just being where he is in his career," Carlyle said. "They're both talented young players, and we think that there's a future for those two guys to be a big part of our defence. We want to make sure we're handling them the right way."
It's a delicate balancing act but one that Rielly has been able to handle decently well himself. He got through the questions about whether the Leafs would keep him or send him back to Moose Jaw of the WHL, then more about possibly representing Canada at the World Junior Championship.
In a 4-3 victory over the Buffalo Sabres on Wednesday night, Rielly got to enjoy a moment just for him and a "pretty good feeling." As centre Nazem Kadri handled the puck behind the net, Rielly cheated toward the net and was wide-open for the pass.
"I just saw Naz with the puck down low," Rielly said. "He's pretty crafty and he came around the net, and I just kind of crept down and he made a good pass and I was able to capitalize."
It was just Rielly's second goal of the season and first since Dec. 16 at Pittsburgh.
"Obviously when you go in a bit of a drought in terms of scoring it's always nice to get one," he said. "I think I was just happy to give the team a lead and it was a big play in the game, but I'm just happy the team won."
One win is good for the Leafs, but the continued progression of the blue-chip defensive prospect is of long-term importance.
"He's obviously got a ton of skill," goaltender James Reimer said. "He sees the ice well and I feel like he's just getting more and more comfortable. He's making solid plays. He's got so much offensive talent and he can see the ice offensively and defensively and he's handling himself well down low. He's got a lot of talent and he seems to be really kind of getting in that zone."
— Follow Stephen Whyno on Twitter at @SWhyno.