COLUMBUS -- The 2015 NHL All-Star Weekend in Columbus was fun, intriguing, exciting and entertaining, but it's over now. It's time to get back to work.

Teams are back at practice Monday and the games start up again Tuesday. Here are 15 storylines to follow as the 2014-15 NHL season hits its stretch drive:

Predicting chemistry on a forward line is as easy as predicting the lottery.

Three players who on paper should be able to jell fail to produce, while three players who might look like misshaped puzzle pieces fit together and make magic.

"The chemistry and synergy of linemates only happens when they're together," Pittsburgh Penguins assistant coach Gary Agnew said. "You can predict as much as you want."

But a prediction is what Agnew and the Penguins coaching staff had to make when right wing David Perron was acquired from the Edmonton Oilers on Jan. 2. Perron is a talented offensive player who scored at least 20 goals three times in his first seven NHL seasons with the St. Louis Blues and Oilers. But almost no one in the Penguins organization had any history with Perron.

"I knew [Kris Letang] a little bit," Perron said. "Knew [Marc-Andre Fleury] slightly, same with [Pascal Dupuis] because we have the same agent."

The only person who had any real relationship with Perron was Agnew, who was an assistant coach with the Blues in 2012-13, Perron's final season in St. Louis. Though it was 48 games in the lockout-shortened season, Agnew said it was more than enough time for him to get an understanding of the kind of player and person Perron is.

SAN JOSE -- San Jose Sharks forward Tomas Hertl can't say he wasn't warned about the danger of a sophomore slump.

As a rookie last season, Hertl scored six goals in his first three games, including four against the New York Rangers. He had 15 goals and 25 points in his first 32 games before damaging two ligaments in his right knee on Dec. 19 during a collision with Los Angeles Kings forward Dustin Brown that kept him out until late in the season.

This season, Hertl has eight goals and 17 points through 47 games entering the Sharks' game Wednesday against the Kings at SAP Center (10:30 p.m. ET; NBCSN).

"Everybody thought it would be a harder season for me," Hertl said. "For some guys it's hard. For some guys it's OK. For me I think it's hard. Maybe before the season, maybe it was in my head that this season I needed to play good because of last season. Maybe it was just in my head. Maybe I put a little bit of pressure on myself."

The team in each conference with the most postseason games played since 2008 and the two teams that played the most games against each other over the previous four seasons will be featured in a Wednesday Night Rivalry doubleheader.

Sidney Crosby and the Pittsburgh Penguins (26-12-7) welcome Patrick Kane and the Chicago Blackhawks (29-15-2) to Consol Energy Center in the early game (8 p.m. ET; NBCSN). Each team is within striking distance of first place in its division.

The Penguins and Blackhawks have combined to win the Stanley Cup three times in the past six seasons. The Penguins' 98 postseason games since the start of the 2007-08 season lead the NHL, and the Blackhawks' 94 are third (tops in the Western Conference).

The Los Angeles Kings (20-14-12) and San Jose Sharks (24-17-6) will play for the 44th time since the start of the 2010-11 season in the back half of the doubleheader (10:30 p.m. ET; NBCSN). San Jose has won 22 of 43 games, but Los Angeles has won two of the three playoff series, each in the past two seasons and in seven games.

Here are five things to watch during the doubleheader:

MONTREAL -- As the race for the Vezina Trophy as the NHL's top goaltender became more and more of a two-man derby, the game Tuesday at Bell Centre between the Nashville Predators and the Montreal Canadiens was looking like it could be a showdown between those leading men.

An injury to Predators goaltender Pekka Rinne prevented that from happening. But someone forgot to tell Carey Price.

The Canadiens' goaltender returned from a one-game absence due to injury to make 36 saves in a 2-1 overtime win against the Predators. In the process, Price made a convincing case for why he might be the Vezina frontrunner instead of his injured rival.

When the Predators scored at 12:10 of the second period on a Mike Ribeiro deflection directly in front of Price, Nashville was outshooting Montreal 26-6 but led 1-0. At one point the Canadiens went 22:15 without forcing Predators goalie Carter Hutton to make a single save.

NEW YORK -- The New York Rangers entered their game against the Ottawa Senators at Madison Square on Tuesday with 15 wins in 18 games. Considering such a run, one would think they would have created some separation in the Metropolitan Division.

Not a chance.

Not when their rival on the other side of the East River, the New York Islanders, has won seven of 10 and reeled off at least three wins in a row seven times this season. The Washington Capitals have earned at least one point in eight of their past 10. As long as Sidney Crosby and Evgeni Malkin are in the fold, the Rangers know it's difficult to envision the Pittsburgh Penguins going away anytime soon.

That's why it was crucial for the Rangers to overcome a sluggish start and earn a 3-2 overtime win against the Senators, capped by Carl Hagelin's goal at 2:55 of the extra period. It allowed the Rangers to move into a tie with the Penguins for second place in the Metropolitan, one point ahead of the Capitals.

The Rangers enter the All-Star break five points behind the Islanders, although they do have two games in hand. The bitter rivals will face each other at Nassau Coliseum when play resumes next Tuesday.

The cowboy hat fit, so Tyler Seguin put it on and embraced the look.

"A hundred percent," Seguin told NHL.com.

This was Oct. 11, 2013, after Seguin, the Dallas Stars center, put the finishing touches on a four-point night at the Winnipeg Jets. He was talking to the media about his new start, his fresh start with a new team, when someone off-camera handed him a cowboy hat with a Stars logo on it.

The hat is the pseudo-trophy the Stars give out to their player of the game after wins. Vernon Fiddler started the tradition last season. Seguin was an easy choice that night in Winnipeg after Dallas' third game of the season, but it was his reaction that left an indelible mark that Stars general manager Jim Nill vividly recalls.

Seguin grabbed the hat and plucked it right down on his head. He smiled. He chuckled. He continued answering questions, but he could hardly get through the three-minute session with reporters without cracking up.

This was one of the first public signs of Seguin, Toronto-born and NHL Boston-bred, wrapping his arms around playing for the Stars.

NEW YORK -- The question for New York Rangers forward Rick Nash was about the club's center depth in general. Nash's answer turned into a plug for the continued improvement of rookie center Kevin Hayes.

"Hayes has impressed me," Nash said. "You think about how mature his game is; he's been playing at a high-level of college for a while and what is he, 22? It's impressive the maturity in his game, especially to go up against a guy like [Joe] Thornton and hold his own."

Hayes has impressed a lot of people around the Rangers this season. He has become as important to the Rangers' success as any other role player.

Hayes was plugged in as the third-line center in his second NHL game. He has been stable in that position since, giving the Rangers the center depth a team needs to have sustained success in an NHL season.

His next test comes Sunday at Consol Energy Center against the Pittsburgh Penguins (12:30 p.m. ET; NBC, TVA Sports, SN), who roll out a 1-2-3 center rotation that is the envy of the League: Sidney Crosby, Evgeni Malkin and Brandon Sutter.

After numerous stops and starts in two-and-a-half seasons as a pro, Pittsburgh Penguins forward Beau Bennett is finally starting to show signs he might have been worth that No. 20 pick in the 2010 NHL Draft.

"He's had some [bad] luck, but it's going good now," Penguins center Brandon Sutter said.

The biggest question for Bennett is, will he stay healthy long enough to fulfill his promise and prove without a shadow of a doubt that he was worth being a first-round pick?

Bennett is a long way from that considering he's played 61 NHL games, including 35 in the past two seasons. But if he can stay out of the trainer's room and off the operating table, he should be an important part of the Penguins' push for another Stanley Cup.

MONTREAL -- The Montreal Canadiens can be a difficult team to understand. They have been hovering around the top of the Eastern Conference for most of the season, yet the Canadiens are rarely mentioned among the elite teams in the NHL.

But here they are with a 28-13-3 record following a 6-4 win at home Saturday against the New York Islanders, who entered the game having won four in a row, including a big 6-3 victory against the Pittsburgh Penguins at home a night earlier.

The Islanders were 6-1-0 this season playing the second of back-to-back games and had won their past four under those circumstances before losing to the Canadiens.

Prior to the game, Montreal talked about the opportunity to prove a point against a team that was getting the accolades around the League that the Canadiens felt they deserved but weren't getting.

"You want to earn respect across the League," forward David Desharnais said. "It's by beating those teams that you're going to do that."