When he was 14 and playing and living in Wilkes-Barre, Ivan Provorov was given an app to install on his iPad and iPhone by his amateur team. The app allowed video downloads of his shifts, so he could study them and improve both himself and the team.

"You could go on your iPad or your phone and the shifts would be broken down,'' he was saying before the Flyers' victory over the Florida Panthers on Tuesday night. "Power play … PK …''

Again, he was 14.

"You've got to be a student of the game,'' said the crusty old 20-year-old. "You have to learn something every day. And there's no limits. You get better and better with every day. That's how you get here. That's how you stay.''

There might be no better explanation for the infusion of youth to the NHL at a position that not too long ago required a lengthy apprenticeship. Consider, for example, the plight of Bob Boughner, Florida's first-year coach, who spent the first five seasons of his professional career learning his craft in various underling leagues such as the ECHL, IHL and AHL before embarking on a 12-year NHL career.

Of the six defensemen Boughner suited up against the Flyers on Tuesday, five were 25 or younger. One, 2014 first overall pick and 2015 Calder Trophy winner Aaron Ekblad, is 21 and already an assistant captain.

When the Flyers lined up against the Capitals the other night, the Caps' second defensive pairing had two rookies. This was partly because of injury (veteran Matt Niskanen was hurt in the previous game), partly because of salary-cap concerns (the Capitals parted with two defensemen from last season's Presidents' Trophy team in the off-season), and partly because of the above-mentioned sea change evident throughout the league.

"Everybody is in way better shape than they were 10 years ago,'' Kimmo Timonen was saying between periods in the press box Tuesday. "I think that helps, too. The skating for these young D-men nowadays is at an unbelievable level. So I think the skating part is already there. It's just a matter of getting the timing and the pace of the game.

"The world has changed, I think.''

There is no better body of evidence for that than the current Flyers. Of the six defensemen playing regularly, three – Provorov, Shayne Gostisbehere and Robert Hagg – are 24 or younger. Each has yet to play two full seasons (Gostisbehere joined the Flyers in December 2015). A fourth, 21-year-old Travis Sanheim, has played in three of the team's first six games and is expected to take a regular spot as he becomes more acclimated to the pro game. Another young blueliner, 22-year-old Samuel Morin, was sent back to the Phantoms at the start of the season only because of the Flyers' depth, and he is expected to be recalled upon the team's first injury among defensemen.

Hagg recorded his first NHL point Tuesday night on a play emblematic of his arduous journey to reach the NHL. A flashier, riskier player in his youth, Hagg has been schooled over his two seasons in the AHL on the little things. Hagg was paired again with Gostisbehere on Tuesday, and his blocked shot sprung his partner for an odd man rush up ice that resulted in the Flyers' second goal.

"Block a shot and get an assist,'' Flyers coach Dave Hakstol said with a smile. "That's not a bad way to do it.''

"It's not going to say in the newspaper tomorrow how I made it,'' Hagg said. "So I will take it.''

"The thing that gets lost in a play like that is the shot block 200 feet away,'' his coach said. "He does a lot of little things. He's doing a lot for a young player, and he's doing them with good confidence. … What I like is he's a worker. He comes in every day, and he works at his game."

That's the other point to this: These aren't your normal starry-eyed rookies entering the league these days. Many feel not only that they belong, but also that they're overdue. Provorov's preparation, to hear him talk about it, is not unlike that of the pitching ace who studies batters' tendencies before starts.

"I don't want to give out details,'' he said. "But you look at how the player is coming to you. What kind of skater he is. What kind of stride he takes, where his hands are on his stick.

"And the longer you play in the league, the more you learn about the opposing players.''

Tuesday night, the Flyers allowed 41 shots on goal although, as Gostisbehere noted afterward, many were wide-angle tries. The Panthers lead the league in shots, by the way. Last year's offense-challenged Flyers were near the top in that category, too.

"They kind of looked like us last year,'' Gostisbehere said.

Hagg's shot block was one of 22 recorded by the Flyers on Tuesday. They have played six games this season alternating goalies, and in four of them, the opposition has scored two goals or fewer. And the most enthralling part of all of this is the thought that it will get only better. Morin is coming. Philippe Myers is right behind him.

And by the time they do, Provy, Ghost and Hagger will be wisened vets.

At least by current NHL standards.