There were a number of people who expressed concern that the marriage between Randy Carlyle and the Toronto Maple Leafs would be a disaster.

Carlyle, who guided the Anaheim Ducks to the Stanley Cup in 2006-07, came to town with a reputation for being a heavy-handed coach who demanded his team play a physical game. Did the Leafs have the personnel to play that kind of a game? How could it possibly work?

Well, it has worked thanks to some creative tweaks to the roster. Now, for the first time since the 2003-04 season, Toronto is headed to the Stanley Cup Playoffs. Here are five reasons why the Maple Leafs are going to the postseason:

1. Goaltending

James Reimer Goalie - TOR RECORD: 18-6-5

GAA: 2.41 | SVP: 0.926

If the Maple Leafs had solid goaltending last season, there is a good chance they would have made the playoffs and Ron Wilson still would be coaching the team. It didn't work out that way, though.

Coming of a season when he burst onto the NHL with great results, going 20-10-5, James Reimer was expected to carry the bulk of the load and got off to a wonderful start, going 4-0-1 before suffering a neck/concussion injury that plagued him the rest of the season. Rookie Ben Scrivens proved he belonged in the NHL but was not quite ready for prime time. Thus, the Maple Leafs fell short once again in their attempt to get to the playoffs.

The Maple Leafs resisted bringing in goaltending help in the summer, electing to go with the same pair this season, and the results have been superb. The team also changed goaltending coaches, replacing Francois Allaire with former NHL goalie Rick St. Croix. Although Toronto reportedly inquired about a few veterans at the trade deadline, no deal was made. Reimer guided them into the playoffs and is entrenched firmly as the starter. The 25-year-old has given the Maple Leafs a comfort in the crease the team has not enjoyed since Ed Belfour departed in 2006.

2. Success on the penalty kill

Through 45 games the Maple Leafs ranked No. 3 in the League in penalty killing with an 87.0-percent success rate. That is in direct contrast from the past three seasons, when they finished No. 28 in 2011-12 and 2010-11 and No. 30 in 2009-10. Toronto never reached a 78-percent success rate in any of those seasons.

The Maple Leafs are much more aggressive in their zone when playing shorthanded. They play more of a puck-pursuit game and support each other with more vigor.

Scott Gordon, the former coach of the New York Islanders and now a Maple Leafs assistant, ran the power play last season, but switched to the penalty kill in 2012-13. The results have been staggering.

"The penalty kill has been a big part of our success this season," veteran defenseman John-Michael Liles said. "Any time you can keep teams from scoring with the man-advantage it's huge. There were just little tweaks. I can't point to one thing and say it has been the difference-maker, but it comes down to everybody knowing their role and playing to their strengths as an individual while also playing to our team's identity."

3. Team Toughness

It was evident seven minutes into the first game of the season, when Mike Brown, who has since been traded to Edmonton, fought Montreal's Brandon Prust in Montreal, the Maple Leafs were not going to be intimidated. It only took 2:38 into the second game, against the Buffalo Sabres, for Colton Orr, who spent most of last season in the minors, to tangle with big John Scott. It hasn't stopped all season and Toronto leads the League in fighting majors, as well as hits.

Last season the Maple Leafs tended to get pushed around by bigger, more aggressive teams such as the Boston Bruins and Philadelphia Flyers. That has not been the case this season.

The additions of hard-hitting forward Leo Komarov and defenseman Mark Fraser have been instrumental in the Maple Leafs being the NHL's most frequent hitters.

"I think we're a lot tougher team to play against now," Liles said. "I think there were times last year when we got pushed around. There will still be times when you will play a physical team and things will heat up; that's the nature of the NHL. But we have a lot of guys in this room that can give some pretty good push back. As a team, we realize we have that in us."

4. Better depth and accountability

Not doing what is expected from you? Then take a seat in the press box. That is the way it is nowadays in Toronto, with even veterans, at times, relegated to healthy-scratch status. The Maple Leafs were quite thin the past few seasons and did not enjoy the luxury of taking underachievers out of the lineup.

When Carlyle didn't like a couple of errant passes made by Liles in New York on April 10, the veteran was replaced in the lineup by Jake Gardiner. Liles, in fact, has been a healthy scratch for 13 games this season. Gardiner has felt the wrath of the coach at times, as well. The 22-year-old made the NHL All-Rookie team last season when he had seven goals and 30 points in 75 games, but has spent much of this season either playing in the American Hockey League or watching from the press box. Cody Franson has established himself as a regular on the blue line now, but only after sitting out three of the first five games. You get the picture.

Obviously, Carlyle believes bigger is better. The Maple Leafs have added tough Frazer McLaren who is 6-foot-5 and 230 pounds; scoring left wing James van Riemsdyk (6-3, 200); veteran forward Jay McClement, who is a sturdy 6-1 and 205 pounds' as well as Komarov, a grinding right wing who plays bigger than his 5-10 frame would suggest. Orr, who was thought by many to be at the end of the line after being sent to the AHL last season, has re-emerged as a bona fide tough guy. Also, Franson (6-5, 213), has emerged as a steady regular.

5. A bright future

The Maple Leafs -- in particular Dallas Eakins, coach of the team's American Hockey League affiliate, the Toronto Marlies -- have done a nice job in developing players at the AHL level to compete for jobs in the NHL.

Without question, Nazem Kadri, the team's first pick (No. 7) in the 2009 NHL Draft, has taken the next step in what promises to be a long and prosperous NHL career, though he clearly remains a work in progress. Until recently Kadri was leading the Maple Leafs in scoring despite averaging just more than 16 minutes of ice time per game, not holding down a place on the top line and not getting any first-unit power-play duty.

Kadri has improved his overall game to the point where he is no longer a defensive liability. He is shifty with the puck, has great vision and a sneaky good shot.

Center Ryan Hamilton, the captain of the Marlies, has proven to be a solid defensive forward since being recalled March 23, and Joe Colborne has shown signs he is getting close to challenging for regular NHL employment.