Armed with a full NHL season under his belt, and a new long-term contract, Nikita Zaitsev knows what he needs to improve on in 2017-18.

As highly acclaimed as he was as a free agent signing, Nikita Zaitsev still had to prove he could play the NHL game after a career solely played in Russia. That’s not an easy jump to make, but the 26-year-old made it work with the Toronto Maple Leafs.

Zaitsev played more than 22 minutes a night for the Leafs, earning a top-four spot on the defense corps and helping Toronto to a surprise playoff spot. But for all the positives that came out of the campaign, this is really just the beginning for the rebuilt Leafs and Zaitsev knows that he personally must improve if the team wants to become a serious contender.

“I got a lot of lessons,” Zaitsev said. “I will think about it this summer and get better. I know what to do.”

The rearguard headed back to Moscow for the off-season, where part of the mission was to get bigger. Already 6-foot-2 and 195 pounds, Zaitsev doesn’t have too far to go in that regard, but the rigors of the NHL became clear to him and the post-season in particular was an eye-opener.

“It’s more simple hockey,” he said. “More battles, more physical – it’s absolutely a different game.”

Along with getting bigger, Zaitsev’s checklist included his skating and his scoring touch. In terms of moving the puck, he’s already pretty good. And throughout the season, he was trusted with taking on the top offensive talents in the league, from Connor McDavid and Sidney Crosby to prolonged action against the Alex Ovechkin-Nicklas Backstrom-T.J. Oshie line of Washington in the playoffs. There were certainly times when he and his partner (Morgan Rielly or Jake Gardiner, usually) would get hemmed in their own zone, but it’s all part of the learning process and it’s important to recognize how the smaller ice surface can mess with a Russian player who has known nothing but the large international-sized ice in his career. For example, decisions must be made much quicker in the NHL and on a young Toronto team, that sometimes led to confusion.

The successes outweighed the struggles however, and the Leafs rewarded Zaitsev with a seven-year contract extension with a cap hit of $4.5 million after the team’s season finished. Expectations will be a lot higher in Toronto for the 2017-18 campaign and the team’s defense has to be better if the Auston Matthews-led forwards are going to see their reign of destruction count for something.

“I look forward to helping the team,” Zaitsev said. “I want to get better every day and be a really important player on this team.”

And he’ll certainly have the opportunity. Though there’s still the possibility of roster movement (more so trade than free agency), the Leafs’ defense corps is largely unchanged. Veteran Matt Hunwick is gone, replaced by another veteran in Ron Hainsey. Rielly, Gardiner and Zaitsev will still be the key members, with growth from Connor Carrick, Martin Marincin, Alexey Marchenko and perhaps the NHL debut of Travis Dermott representing the great unknowns right now.

Getting in a playoff series early, particularly one that went back and forth and featured tons of overtime, was a great primer for the young squad and Zaitsev isn’t discounting its importance in the long run.

“When I was playing in KHL playoffs at 18, it was unbelievable,” he said. “It’s the best opportunity. We’ve had our 19-year-old guys in the playoffs now, so we will grow and grow fast. But next year will be tougher for us because everyone knows we’re a good team. It’s going to be an interesting year. It’s going to be fun.”