"The points are one thing, but just the little things he does out there are more impressive. You know he's going to throw points up. In a bad year, he's going to get 65. It's incredible."
Karlsson's physical gifts, as illustrated in Potvin's anecdote, are the foundation to his extraordinary skating ability.
Ottawa assistant general manager Pierre Dorion scouted Karlsson at an under-18 tournament in 2008.
"He was 5-10 and just under 160 pounds, but you saw something special there as far as puck skills," Dorion said. "Skating was good, but wasn't as dimensional as it is now. You saw the puck skills and the offensive ability and you just said, 'Wow.'
"I remember calling [Senators general manager] Bryan [Murray] and saying, 'I just saw a guy who I think can be a star in the NHL.' "
At the 2008 NHL Draft, Murray traded up to take Karlsson, because he heard the Anaheim Ducks were going to select him with the No. 16 pick. Ottawa, at No. 18, made a trade with the Nashville Predators to move up to No. 15.
"Was it a bit of a gamble?" Dorion said. "At that point in time it was, but you knew he was going to go in the first round some time.
"I thought he was going to be a real good player. Remember how good Danny Boyle was? I thought he'd be a Danny Boyle with more skating ability.
"But to be the dynamic, special player that he is now? I'd be lying if I said that."
The Senators have five players with 50 or more points this season. For Karlsson to have 81 points means he is driving the offense almost singlehandedly.
Ryan said Karlsson's skating ability allows him to carry pucks out of the defensive zone and seamlessly positions him as the Senators' offensive catalyst.
"When he breaks the puck out himself, he's already in the rush," Ryan said, "so he gets a lot of points right there, which a lot of other defensemen don't have the opportunity to do.
"I think the best offensive defensemen make great first passes, but they don't join as much as he does. He's three strides away from catching a guy 15 or 20 feet ahead of him, which allows him to be creative like that."