NHL: Preseason-Philadelphia Flyers at Boston Bruins

Bruins defenseman Urho Vaakanainen, left, defends against Philadelphia’s Kevin Hayes during the first period on Monday night.

BOSTON — Urho Vaakanainen is one of the Boston Bruins’ most promising prospects.

On Monday against the Flyers, some of the learning curve he faces was on display.

The 20-year-old is a long shot to get early playing time, but is likely the first one in if there’s an injury on the blue line while Kevan Miller and John Moore remain out. He played in two NHL games last season — one of which was cut short due to concussion — but there’s a lot of hope for him to become one of their leading defensemen down the road.

The preseason has been a good example that while he has shown flashes, he’s also still a work in progress.

“I don’t think he skated well enough to skate with people, to break out pucks,” Bruins head coach Bruce Cassidy said following Monday’s game. “One of his strengths is his foot speed, and his defending with his foot speed. He got beat wide once tonight, that’s not typically his game, he’s pretty good that way. So, I thought his feet weren’t engaged tonight enough in the game.”

A rough preseason game isn’t the end of the world for anyone, especially someone with as much potential as Vaakanainen. For him, the most important thing early on is staying healthy after having a season of injuries.

But it’s not an unimportant camp, either, especially when he got looks on Monday working with the top power play unit and he didn’t play at his best.

“(The coaching staff) give me tips and stuff all the time,” he said. “I feel like it helps.... I felt like my feet (weren’t) really moving. I felt pretty slow (Monday night), I don’t know why. (Cassidy) was right about that. It’s a big part of my game to keep my feet moving to make big plays, be good with the puck.”

Vaakanainen likely will never be the offensive quarterback type of a Torey Krug or even Charlie McAvoy, but his skating and puck possession are his strengths and having off nights skating doesn’t bode terribly well.

They’re not overly concerned; Vaakanainen is a young player, and likely Providence-bound for most of the season while the blue line is healthy. But they’d like to see some progress, and at the least consistency skating.

“Those are things that we can work with him on, but his feet need to be moving every night,” said Cassidy. “I thought he could have been better in that area (Monday), being a little bit more of a factor. I thought (Jakub) Zboril did a pretty good job that way, breaking out, getting up ice and supporting the rush. Not as much for Vaak (Monday night).”

If there was any year for Vaakanainen to have time to develop, it’s one where the Bruins have a plethora of depth on the back end, with reinforcements on the way. He knew heading into camp it would be a long shot to get regular playing time, but that hasn’t been overly discouraging.

He does have a shot to get some looks — or, as Cassidy described on Tuesday for the young players looking for spots, at least being the first callup — but consistency each night is the biggest key to that.

“You just have to do your best, and see where you get,” said Vaakanainen. “You can’t think about stuff like that. Just try to play your best game.”