Generally speaking, when the Habs were up, the Leafs were down, which really has been most of the time.
But when the Leafs were up -- at least relatively, in the way the Canadiens would define "up," as in Stanley Cup victories -- the Habs would be down, as was the case through the late 1990s and early part of the 21st century.
Now, with the postlockout environment dictating some very different challenges for NHL squads on both sides of the Canada-U.S. border, it's intriguing that both Original Six clubs find themselves simultaneously gasping for air in the Eastern Conference standings. The other four Canadian teams appear solidly in contention for postseason berths, while the Habs and Leafs aren't nearly so well positioned.
For the Canadiens, it's a huge disappointment, particularly given the team's strong play early in the season. The firing of coach Claude Julien illustrated the panic in Montreal over the possibility of missing the postseason. But after two quick wins, GM-coach Bob Gainey hasn't been able to do any better as Julien's temporary replacement.
For the Leafs, however, it's possible this was, at least to some degree, predictable. Historically speaking, working with change has not been this organization's strongest point.
Toronto didn't fare well in the years after the NHL's 1967 expansion, which doubled the number of teams to 12 from six. Indeed, when the WHA started up in the early 1970s, the Leafs were also one of the teams that misjudged the new league most, and ended up needlessly losing a series of quality players.
As bad as that was, the Leafs were even worse in their response to the merger with the WHA in 1979, and soon were the worst team in hockey after briefly becoming competitive in the latter part of the '70s under Roger Neilson.
When Europeans started pouring into the NHL in the late 1980s, meanwhile, the Leafs were among the teams that reacted least effectively.
Now, with the constant presence of a salary cap hovering over the operations of each and every NHL club for the first time in the league's history, the team that Conn Smythe built is once more struggling to adjust to the winds of change.
At least Boston GM Mike O'Connell has admitted the Bruins' postlockout plan was not an effective one, although that might not be enough to keep O'Connell employed.
The Leafs, however, always operate as though they have some manifest destiny, some larger purpose, despite going so long without a championship.
Maybe it's the sellout crowds that appear, regardless of the team's record. Maybe it's the fact that the further the last Cup victory sinks into the rearview mirror, the more popular the team seems to become. Maybe it's the fact that with its own TV channel, the team has the ability to not only manufacture its own propaganda, but does so in a way that seems to convince the players and managers that they are worthy descendants of a proud tribe, regardless of what the win-loss column says.
These days, it doesn't say very nice things, particularly after six consecutive losses and seven defeats in eight games. After riding reasonably high in the conference playoff race most of the season, the Leafs have fallen to ninth and seem stabilized there only because Montreal is showing no signs of revving up its engine anytime soon.
The Leafs are unique in Canada, and probably only matched in the United States by the Rangers and Red Wings, for the fact they have fans in every NHL city, and hordes of them in Vancouver, Edmonton, Calgary, Montreal and Ottawa.
Whenever the Leafs play in those cities, their supporters gobble up tickets to the point that they sometimes engineer a noisy vocal majority for the visitors.
They also drive the national television package, whether it's on TSN, Sportsnet or the venerable "Hockey Night" in Canada on CBC, the country's national broadcaster.
There's an argument that can me made, then, that the Leafs are an important but supremely unmotivated franchise, or at least one motivated not nearly enough to urgently battle for a Stanley Cup.
When you consider that since the Leafs last made the Stanley Cup final in 1967, the Canucks have been there twice, the North Stars were there twice and their Dallas offspring twice, the Carolina Hurricanes and Washington Capitals have both made the journey once and the nearby Buffalo Sabres have been there twice, you begin to understand just how comprehensive the Leafs' ineptitude has been since their last stab at glory.
The Leafs have come close, really, on just one occasion, losing out on home ice to the Los Angeles Kings in Game 7 of the 1993 Western Conference finals.
For years, the Leafs lived off their financial muscle, particularly in the last decade, when they papered over a chronic inability to draft and develop young players by buying one expensive veteran after another.
It didn't bring them a Cup, but it kept them in the playoffs.
Now, it appears at least possible, although there's much time left in the season, that the Leafs have once again been caught struggling with change.
If the Bruins now admit they had a flawed plan coming out of the lockout, it would appear the Leafs' scheme for postlockout dominance was only slightly less suspect. They are essentially maxed out at, or very near, the $39 million salary cap, yet the team is proving to be far less competitive than the leaders in the East.
Specifically, they have found themselves on the losing end of six consecutive decisions to division rival Ottawa, the first two by shutout and the last four by the scores of 8-0, 8-2, 7-0 and 4-3.
The latter two results came last weekend, when the Leafs and Sens played one of those peculiar two-games-in-three-days-at-the-same-arena deals, with both matches at newly named Scotiabank Place in the Canadian capital.
Until Tie Domi, of all people, scored in the second period of Monday's game, the Sens were on a run during which they had scored 13 straight goals against the Leafs. The embarrassing imbalance between the two clubs is a damning indictment of the Leafs players, of course, but also of coach Pat Quinn and GM John Ferguson.
It's Quinn's job to organize the team to at least be competitive, even against superior opponents. It was Ferguson's job to drive the Leafs' bus out of the lockout in such a fashion so as to be even more competitive than was the case before the lockout.
Both, based on recent results, have failed. Ferguson is in only his second full season with the club and has wiggle room, but Quinn has been around for eight seasons and could well be in trouble, although his status as head coach of Team Canada for the upcoming Winter Olympics gives him some political insulation against dismissal.
The reasons behind the Leafs' recent slide are straightforward:
" The club is in the bottom third of the league in team defense, at least partially because of a terrible lack of team speed.
" Goaltender Ed Belfour, 40, is having his worst NHL season statistically.
" An imbalance in home games versus road games in the first half is now seeing the club forced to take its show on the road, and the results haven't been pretty.
" Captain Mats Sundin, who did not play during the lockout, is on a 23-goal pace.
There is also talk of simmering unrest in the dressing room, with Jason Allison figuring prominently as a player likely to be traded because he hasn't fit well with the dominant veteran group in the dressing room.
From Ferguson to principal owner Larry Tanenbaum, all of the key voices in the organization are preaching calm and vowing that major changes, such as firing Quinn, are not being contemplated.
If that is true, it again underlines the easily satisfied nature of this franchise. In the last two Stanley Cup playoff competitions, the Leafs have won only one round, yet the club speaks of Quinn and his staff in unquestioning and reverential terms, as though all are carrying the bejeweled burden of multiple Cups on their fingers.
Lou Lamoriello remade the N.J. Devils on the run during the season and roared past the Leafs in the standings, yet there seems to be little or no urgency in the Leafs' hockey office.
With only about $16 million committed to players next season, and with the salary cap expected to move above $41 million, the Leafs are in an enviable position going into the summer shopping season, particularly if a variety of appealing free agents aren't re-signed by their clubs before then.
That, however, has the Leafs looking toward next year.
Damien Cox, a columnist for The Toronto Star, is a regular contributor to ESPN.com.