Seattle coach Steve Konowalchuk said Barzal had no issues refocusing on helping his junior team.
"Getting Matthew back was a huge moment in our season because he's our captain and such a big part of our leadership group," Konowalchuk said. "He's also obviously one of the best players in junior hockey."
Barzal immediately began showcasing the skills that made him so desirable to the Islanders.
In 41 WHL games, he had 79 points (10 goals, 69 assists). He also helped Canada win a silver medal at the 2017 IIHF World Junior Championship with eight points (three goals, five assists) in seven games.
"When I was with the Islanders the game was always being played at a high tempo," Barzal said. "I tried to play the same way here, keeping the game at top speed."
At the same time he was watching every Islanders game he could and was rooting for them to reach the Stanley Cup Playoffs. They finished one point behind the Toronto Maple Leafs for the second wild card from the Eastern Conference.
"I couldn't watch all of their games but I probably saw 30 or 40 after I got back to Seattle," he said. "They were great in the second half of the season. I thought they were going to get there, and I was cheering for them. Not just because of playing for them, but because I have so many friends on the roster."
Those friends got to cheer for Barzal during the WHL playoffs. He had 25 points (seven goals, 18 assists) in 16 games and was named playoff MVP. He also helped Seattle defeat Regina to win the league championship and advance to the Memorial Cup for the first time.
"It was tough last year when we lost in the [WHL] final, but winning this year made it all worth it," he said. "We worked hard, and it was great to get the reward of lifting the [Ed Chynoweth] cup.
"It also means we've got a chance to win another championship."