When naming the top five players in NHL history, few can debate that Wayne Gretzky, Gordie Howe, Bobby Orr and Mario Lemieux are absolute musts in the conversation. Is this year's Conn Smythe Trophy winner next?

"I'd put Sidney Crosby right there at No. 5," former NHL goaltender and current NBC analyst Brian Boucher told ESPN.com before watching Crosby hoist the Stanley Cup for the third time in his 12-year career, following the Pittsburgh Penguins' 2-0 Game 6 victory over the Nashville Predators on Sunday night. "We're watching greatness. For people to hate on it, I get it, because maybe you're not a fan of the Pittsburgh Penguins. But if you're a fan of watching true greatness, to me, that's it."

Crosby is just the third player in NHL history to win the Conn Smythe (as the most valuable player of the Stanley Cup playoffs) in back-to-back seasons, joining Philadelphia Flyers goaltender Bernie Parent (1974, 1975) and Lemieux (1991, 1992). Crosby has now won three Stanley Cups and two Olympic gold medals, along with golds in the World Junior Championships, the World Championships and the World Cup of Hockey.

Yet the respect of the hockey world has come begrudgingly.

"I feel like he's always having to prove people wrong," said former teammate Colby Armstrong, now a radio analyst with the Penguins. "I know it's crazy to say that about probably the best player of our time right now, with his Stanley Cups and all his awards. But there always seems to be something hanging over him. People saying he's a crybaby. The concussions. He's not what he used to be.

"I don't know what else he could do to not be the villain. He's the best player in our game, alongside Connor McDavid, but it seems like people are always looking to vilify him when he does nothing but make unreal plays and find ways to shine on the biggest stage. If there is anything I have learned about him, it is that when the chips are on the table in the Final, he's found a way to get it done."

Armstrong was a 22-year-old rookie with the Penguins when he saw Crosby step onto the Mellon Arena ice for his first NHL training camp, in 2005. "We had heard a lot about him, but YouTube was just kicking off, so there wasn't much video any of us had on him," Armstrong recalled. "I was like, 'Holy smokes, look at this guy.' To see what he could do at 18, his talent level and the way he competed, was just insane."

During Crosby's rookie season, Armstrong was playing for the AHL Wilkes-Barre/Scranton Penguins when he drove to Philadelphia to see a game between the Penguins and Flyers on Nov. 14, 2005. During a battle with former Flyers defenseman Derian Hatcher, Crosby took a stick to the mouth and parts of his two front teeth were sawed off.

"He throws his helmet down, all upset," Armstrong recalled. "His mouth is bleeding, his teeth are chipped. He's going up against an old-school guy like Hatcher, one of the baddest dudes in the league, and the fans were all over him. Sid was the young kid on the block and he kind of had to answer the bell and earn everybody's respect."

After getting stitches in his lip, Crosby came back to score in overtime, beating Antero Niittymaki with 46.7 seconds remaining. He had two goals and an assist in that 3-2 win.

Face it, Sidney Crosby is one of the best ever. AP Photo/Mark Humphrey

"I remember his celebration," Armstrong said. "He was all angry and smiling at the same time. In my mind that was one of his defining moments."

As a rookie, Crosby became the youngest player in NHL history to record 100 points (he had 102), but the Penguins finished with the worst record in the Eastern Conference and his reputation as a referee whisperer was growing, especially among NHL veterans.

"When he came into the league, a lot of us wanted to see if this kid was the real deal or not," Boucher said. "Early on in his career as an opponent, maybe the one thing that stood out, that maybe annoyed you, is that he always seemed to be complaining and looking for calls. A lot of veterans don't really care for that stuff because even though you may be a great player, you've got to earn those calls. I think over the last couple years you see a lot less of that [complaining] and you see more of a guy determined to fight through stuff."

Evgeni Malkin joined the Penguins during Crosby's second NHL season, when the Penguins made it to the playoffs for the first time in six years. In Crosby's third NHL season, the Pens made it to the Stanley Cup Final, and Crosby recorded 27 points in 20 playoff games, but Pittsburgh lost a six-game Final to the Detroit Red Wings. The following year, in the 2009 postseason, Crosby captained the Penguins to their first Stanley Cup since 1992, and had 31 points in 24 playoff games.

In his fifth NHL season, Crosby won his first Olympic gold medal and his first Rocket Richard Trophy after tying Steven Stamkos with a league-high 51 goals. The Penguins were eliminated by the Montreal Canadiens in the second round that season, and midway through the 2010-11 season Crosby suffered his first in a series of concussions that robbed him of parts of two NHL seasons.

"I've had concussions, and I've never really talked to him about his future or what the damage has been," Armstrong said. "You would think [the concussions] would affect him, but it's tough to say that when you look at the way he's playing now. I look at the way he goes into traffic and the slashes and hacks he gets. He gets cross-checked in the head against Washington [in Game 3] and he misses one game. Just watching him play, he can somehow move by it."

Crosby rebounded from his concussions to record 104 points in 2013-14, his fifth NHL season with more than 100 points, but the Penguins failed to get past the second round in 2014 and 2015, and by midway through last season, many began to wonder if Crosby's days as an elite point producer were nearing an end -- at the age of 28.

Crosby had just 19 points through 28 games, and the Penguins' power play was 26th in the NHL, when general manager Jim Rutherford fired coach Mike Johnston and replaced him with Mike Sullivan on Dec. 13, 2015.

"What's really unbelievable is that if we go back a year-and-a-half ago, before they made that coaching change, we're not even close to having this same conversation," Boucher said. "We were wondering if [Crosby] was starting the downside of a career. There were a lot of questions about that."

Boucher said that while Sullivan's aggressive, up-tempo style has invigorated Crosby, the infusion of Conor Sheary, Bryan Rust and Jake Guentzel -- and Crosby's ability to raise their games to another level -- has helped fuel the Penguins to back-to-back championships while cementing Crosby's legacy as a selfless teammate.

"There are a lot of veterans who have played in the National Hockey League who would say to those guys, 'Hey, get me the puck,'" Boucher said. "But he's very inclusive and very supportive, and he's a big reason those young players are having success. They feel comfortable playing with a star like Sidney Crosby, and that tells me he's a tremendous teammate."

Sidney Crosby was the center in more ways than one for the Penguins. Christopher Hanewinckel-USA TODAY Sports

"He can go down the entire Penguins lineup," Armstrong said, "and tell you five good things about every guy and how much he means to the team, even the guy who isn't playing. He has a large amount of respect for what everyone brings to the team. I hate to use a cliché term like down-to-earth, but when you have a guy like him being that inclusive, it bleeds through your whole locker room."

Crosby finished the regular season tied for second behind McDavid (100 points) with 89 points, and finished second behind Malkin with 27 playoff points. But Crosby's ability to steal the show when playoff series are on the line impresses even his most scrutinous critics.

In Game 5 of the Stanley Cup Final, after the Predators had stolen the series momentum with consecutive lopsided victories in Nashville, Crosby drew a penalty on his opening shift, the Penguins scored on the ensuing power play, and he set up three more goals in a 6-0 rout that swung the series back into the Penguins' favor.

"When you can elevate your game when the stakes are higher and when you're needed the most, that's the mark of greatness," Boucher said. "After drawing that penalty, Malkin joins the party, [Phil Kessel] joins the party, and when you have that, they're a team that's tough to beat. And it's all because Crosby started it.

"The thing that stands out to me is this guy is so driven and so tenacious. I told my son this: 'If you're going to watch one guy play hockey and model your game after, it's Sidney Crosby. He doesn't give up on plays, he gets his nose in there and he works. He's driven.'"

Performing at the highest level in games that mean the most ultimately will serve as Crosby's legacy and cement his place in hockey history, Armstrong said.

"Everyone wants to count Stanley Cups, and obviously, Mario was the Sidney Crosby of his time, bringing Cups to Pittsburgh and saving the team from moving post-career," Armstrong said. "With the Penguins drafting Crosby and winning three Stanley Cups under his captaincy, I think he's got to be right up there with all those greats in the game that have given so much. He's in a special group with those guys -- in a bubble all by themselves at the top -- and there's a gap to everyone else."