"This guy is a special kid," Stamkos told ESPN.com on Tuesday. "I think he's better than me right now. I wouldn't have a second thought on saying that."
Stamkos, 25, also said McDavid is better than he was at 18 years old.
"Oh, he's way better," Stamkos said. "He is good. The best I've seen for a player that age."
Crosby, for his part, was not surprised by Stamkos' comments.
"You know what? From what I've heard, [McDavid has] looked really good this summer. If he's saying that, I believe it," Crosby said.
Although he has watched McDavid only via highlights and does not know him well, Crosby said he believes McDavid is well-equipped to handle all that awaits him.
"I mean, how many 18-year-olds have his ability, right?" Crosby said.
McDavid was picked No. 1 overall by the Edmonton Oilers after putting up 120 points in 47 regular-season games in his final season with the Erie Otters of the Ontario Hockey League.
Information from ESPN.com's Scott Burnside was used in this report.