And they weren't disappointed when he made the opening-night roster this season at age 19. He scored six goals in his first three games, including a dazzling four-goal game against the New York Rangers on Oct. 8; he was the youngest player since Jimmy Carson in 1988 to score four in a game.
"He just thinks the game at a higher level," Sharks general manager Doug Wilson told USA Today earlier this season. "He's a pretty well-rounded player. He plays in all three zones. He's defensively aware; he's got the sense to play with some high-end players."
Hertl had 25 points to lead all rookies when his season came to a crashing halt Dec. 19 against the Los Angeles Kings. A knee-on-knee collision with Kings captain Dustin Brown left Hertl with two damaged ligaments in his right knee. The ligaments were surgically repaired Dec. 31.
It was feared Hertl would be lost for the season, but he began skating in late February and returned to the lineup April 11, with two games remaining in the regular season.
The Sharks haven't struggled much since Hertl was injured, but his potential return to form adds an extra element of explosiveness to the lineup at the most important time of the season.
"I am very excited because it's four months of not playing hockey," Hertl said the day he returned. "I'm very happy [it's] before playoffs. I hope it's all good and knee is OK. I'm ready to play, and ready to play in the playoffs."
When Hertl went out of the lineup, he was playing on the Sharks' top line, alongside Joe Thornton and Brent Burns. Joe Pavelski has found a home there for now. Though Hertl could regain that prime spot, coach Todd McLellan has the luxury of not needing to rush the rookie.
McLellan said it would be an ongoing assessment to see where Hertl best fits in the lineup.
"We'll play it shift-by-shift," he said. "He'll give us an indication fairly early of what his condition level is like, and timing, and all that."
McLellan tried to downplay Hertl's return; because Hertl turned 20 a month before his injury and he has fewer than 40 games of NHL experience.
"It's an exciting thing to see him back in the lineup," McLellan said the morning it was announced Hertl would return. "But we're tempering that excitement. … If he comes out and scores and has a great game that's fabulous, but this young player hasn't played since early December."
However, the addition of a player as dynamic and gifted as Hertl only bolsters the Sharks' already strong Stanley Cup chances.