The 22-year-old from Minnetonka, Minn., has befuddled the Boston Bruins with his skating and vision on the ice in the NHL playoffs.
"He's a special player and he separates himself with his skating ability," Toronto coach Randy Carlyle said after Toronto's 2-1 win in Game 6 Sunday night. "And he's playing at the level that we expected he would start with us.
"So are we surprised by it? No, not really. This is what our expectations were for the player. The bottom line is Jake's a puck-moving NHL elite-level defenceman. And there's areas of his game like any young player, like any player, have to be improved on. And that's what we asked of him."
For Carlyle, who is stingy with compliments because he sees room for improvement in just about everyone, it was rare praise.
Gardiner logged 21:19 minutes of ice time Sunday, second only to captain Dion Phaneuf's 25:16.
He played 75 games for the Leafs last season, earning all-rookie honours. But he only took part in 12 games this year under Carlyle, who appreciated his offensive skills but was wary of the player's defensive skills.
Gardiner can offer a risk, reward game, making great plays but occasionally coughing up the puck. But against the Bruins, he had a goal and three assists going into Game 7 Monday night and was a difference-maker.
Carlyle spent plenty of time watching the AHL Marlies during their playoff run last season and the lockout. Gardiner and forwards Matt Frattin and Joe Colborne were identified as players to watch.
"The level of play that they were playing in the American Hockey League proved to us that they were going to at least earn an opportunity to get some games with us," Carlyle said.
Gardiner had already stood out, while there had been some questions about Colborne's development. Frattin, meanwhile, had been on a roll until he was injured in the AHL playoffs.
"So we had three which we considered prospects to play on our team," said Carlyle. "When they were going to play was going to be up to them.
"Now they're living it. And I don't have any qualms about putting those kids in situations as long as they understand that defence is first in their first foray. The responsibility that they have is they can't be noticed for their negatives. As long as they just go through the game and they don't hurt you, then that's a huge step for them."
Frattin, a 25-year-old from Edmonton who has seen 82 regular-season games with the Leafs over the last three seasons, has seen action in two playoff games against the Bruins.
That has included stints on the top line as Carlyle looked to keep sniper Phil Kessel against Bruins stopper Zdeno Chara.
Colborne, 23, made his playoff debut Sunday, coming in for the injured Tyler Bozak. He played well but may have earned the wrath of Carlyle when the coach learned that the six-foot-five Calgary youngster had told reporters he was going to play in Game 6, but had been instructed to keep it quiet.
Colborne played in just 16 regular-season games for the Leafs over the last three seasons.
Frattin played 15:36 Sunday night while Colborne logged 15:05.
Monday's Game 7 between the Bruins and Maple Leafs is just the third between the Original Six teams in their 89-season rivalry — and for the first since April 7, 1959, when Toronto won 3-2 at Boston Garden to win their semifinal series.
The Leafs are appearing in their first Game 7 since April 20, 2004, when they defeated Ottawa 4-1 in the first round.
Toronto is attempting to rally from a 3-1 deficit to win a best-of-seven series for the second time. In 1942, the Maple Leafs made history by overcoming a 3-0 deficit to beat the Detroit Red Wings in the Stanley Cup final.
For the Bruins, it's their eighth Game 7 in the last six seasons. In 2011, the Bruins became the first club in NHL history to win three Game 7s in one playoff year, eliminating the Montreal Canadiens and Tampa Bay Lightning before defeating the Vancouver Canucks to win the Stanley Cup.
Boston was eliminated in seven games by Washington Capitals in the first round last year.