The coaching change in the middle of December that saw the Pittsburgh Penguins replace Mike Johnston with Mike Sullivan is an obvious turning point in their season. Everything from their style of play, to their record, to their current run this postseason reflects that.

But Sullivan's promotion from the Penguins' AHL team in Wilkes-Barre/Scranton isn't the only one that has helped spark their turnaround. In the month that followed the coaching change, the Penguins started making a series of call-ups from the AHL to help bring some much needed speed and youth to their lineup.

It was at that point that Conor Sheary, Bryan Rust and Tom Kuhnhackl were given an opportunity to regularly play in the NHL. It was clear from the very beginning that Sullivan trusted them, believed in them, and was going to give them an opportunity to succeed.

Just a few months later, Sullivan and the Penguins are being rewarded for that trust. They are not only playing in the NHL, they are scoring massive goals in the playoffs.

It was Sheary that scored the overtime goal in Game 2 on Wednesday, which came after he scored a goal in Game 1 of the series. Rust has six goals this postseason, including one in the Stanley Cup Final and both tallies in the Penguins' Game 7 win in the Eastern Conference finals.

Together, the trio of Sheary, Rust and Kuhnhackl has 12 goals this postseason, and that does not even begin to get into the contribution of the biggest AHL callup, goaltender Matt Murray.

It has been fascinating to watch the development of the forwards over the course of the season.

At the start of the year they were barely a blip on the radar outside of the Penguins' organization (and maybe even in it).

Sheary was an undersized, undrafted free agent that had a promising debut season in the AHL in 2014-15 and continued it through the first part of this year. Rust and Kuhnhackl were mid-round draft picks in 2010 that had put up decent numbers in the AHL, but nothing that would have indicated they would be major players on a Stanley Cup contending team. They were probably starting to reach a point in their career's where their status as prospects was starting to run out.

Conor Sheary is one of the young players making a surprising impact for the Pittsburgh Penguins USATSI

But almost as soon as they arrived in Pittsburgh you could see the potential. The production wasn't always there (and early on that was a concern), but their speed was an immediate issue for opposing teams to defend. It is a trait that Sullivan has repeatedly referred to this season as their "competitive advantage," and it has become the Penguins' calling card over the past five months. Not only because of the callups, but also the additions of Carl Hagelin and Trevor Daley in trades.

Together, they helped give the Penguins a balanced lineup where all four lines could actually play and complement their superstars at the top of the roster, something they had not had in years and had been one of their biggest failings as an organization.

But what has really stood out about players like Sheary and Rust is they are not just bottom-six depth players. They are playing on top-lines, next to some of the best players in the world, and making meaningful contributions. They are not just along for the ride.

Sheary has found a spot this postseason on the Penguins' top line next to Sidney Crosby and Patric Hornqvist, a trio that has combined to score nine goals when they are on the ice together during 5-on-5 play. Even though his hands can't always catch up with his feet, Sheary's speed and ability to come away with possession of the puck against bigger, stronger player is always noticeable.

Rust has been a recent addition to a line with Evgeni Malkin and Chris Kunitz, a line that has outscored its opponents by an 8-0 margin since they started playing together just a couple of weeks ago. He was a constant thorn in the side of the Lightning in the previous round, not only scoring three goals in Game 6 and 7 of the series (including both Penguins goals in their Game 7 win) but by blowing past Victor Hedman, one of the NHL's best defenseman, on multiple occasions to help create goals and chances. Like this play in Game 5.

If there is a lesson here, again, it is that speed and skill can overcome a lot of other shortcomings, and more teams are going to start realizing this. It is hard to imagine players like Sheary or Rust with their skillset and physical build getting an opportunity and having this type success in the NHL 15 years ago.

In a lot of ways it is fitting that these guys are making these plays for the Penguins because they are a perfect representation of what this team has become. Fast players that for one reason or another were counted out, overlooked, or had simply fallen out of favor in some way and have simply found a way to make everything work (and this also applies to a lot of the veteran additions on the team, whether it's Hagelin, Daley or even Phil Kessel).

After they arrived in Pittsburgh and started to get their opportunity it had been common to simply refer to them as "the Wilkes-Barre guys."

After a game in the middle of February, right around when the Penguins were showing signs of putting everything together on the ice, Ben Lovejoy, one of the more respected veteran players on the team, was asked about "the Wilkes-Barre guys" and their contributions to the team.

His response: "They are not Wilkes-Barre guys. They are Penguins now. Pittsburgh Penguins."

And they have proven to be more important Pittsburgh Penguins than anybody could have ever imagined at the start of the year.