Yzerman said April 10 he was hoping Stamkos, who missed the final 65 games, would be ready for next season.
"Whether he needs a little more time in the fall or not, I don't know that, but [with] a good offseason, I'm confident his knee is going to be great and he's going to come out and be the great player that he is, the dynamic player that he is," Yzerman said.
Yzerman also said he expects forward Ryan Callahan (hip) to be ready for next season.
During the final weeks of the regular season, Stamkos practiced with the Lightning and was said to be day to day, though Stamkos said he wasn't that close to returning.
"I think we just got a little ahead of ourselves," Stamkos said April 10. "I had two really good skates and practices and wanted to get some touches in certain areas of the rink with the power play and stuff. There was no setback, [but] it didn't progress as fast as I originally thought it would that week."
Stamkos, 27, had 20 points (nine goals, 11 assists) in 17 games this season. The Lightning finished 42-30-10, one point behind the Toronto Maple Leafs for the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
Stamkos signed an eight-year contract worth $68 million through 2023-24, an average annual value of $8.5 million, on June 29, two days before he could have become an unrestricted free agent.
