Five storylines to follow in 2012

On March 10, Major League Soccer kicks off its 17th season, making it the longest-running fully professional soccer league in the U.S. The North American Soccer League, which enjoyed a brief halcyon period in the late 1970s before fading fast, lasted only 16 seasons after all.

Today, we come to realize that the conversation has almost imperceptibly meandered from "Will this league survive?" to "Just how big will this league get?" Last season's average attendance of 17,872 surpassed that of the NBA's (17,323) and NHL's (17,132) 2010-11 seasons -- although, in fairness, those leagues have a regular season that's more than twice as long. And some wonder just how far MLS is from putting a real dent into the more popular leagues, as the NBA and NFL emerge anew from lockouts, while sentimental favorite Major League Baseball appears to be less and less at the forefront of the national consciousness, even if its attendance figures continue to be strong.

Ultimately, MLS -- taken more seriously in knowledgeable soccer circles than ever before -- remains worthy of its spot in the mainstream and will attempt to draw more fresh eyeballs this season. And it is well equipped to do so, with more star power and a bigger footprint -- in teams, air time and media coverage -- than ever before.

Within the grander narrative of MLS's growth, there are a slew of compelling subplots to watch for this season. Here are the biggest storylines heading into the 2012 season:

1. The rise of the powerhouses

As MLS grows and the financial reins on its clubs are gradually loosened, it's only natural that the more ambitious clubs, backed by big markets and powerful owners, jostle for position at the front of the pack.

By stocking up on pricey designated players who can make a real difference on the field, the Los Angeles Galaxy and New York Red Bulls have made their intentions crystal clear: domination.

The Galaxy saw its sizable investments pay out at long last in 2011, when DPs David Beckham, Landon Donovan and Robbie Keane led them to the championship. The Red Bulls, on the other hand, weren't able to leverage the presence of Thierry Henry and Rafa Marquez into more than a second consecutive first-round exit from the playoffs. Like the Galaxy, New York has armed itself further this winter and is rumored to be adding former Germany star Michael Ballack as its third DP in July.

But will they put it all together at last, or will they, as their rivals' fans like to say, be more Pink Cows than Red Bulls? As for the rest of the league, will a real gap between rich and poor open up? Can other emerging "big" clubs like the Seattle Sounders and Sporting Kansas City keep up? Or will the savvy smaller clubs like the Houston Dynamo and Real Salt Lake continue to upset the natural economic order?

2. Can an MLS team win the CONCACAF Champions League?

In 2011, Real Salt Lake stunned the continent by reaching the final of the CONCACAF Champions League, the premier club competition for teams in North and Central America and the Caribbean. RSL even took a 2-2 aggregate lead into the second leg before falling 1-0 to Monterrey.

This season, three MLS teams are still alive in the 2011-12 tournament, which resumed with its quarterfinals stage Tuesday. Two of them, Toronto FC and the Galaxy, battled to an entertaining 2-2 first-leg draw, and guarantee an MLS team in the semis. There, the winner could face the Sounders, provided they get past Santos Laguna (the Pacific Northwest side will take a 2-1 aggregate lead to Mexico next week).

The recent accomplishments of MLS teams in the CCL and the strong lineups they now face in every game suggest that victory by a Mexican club is no longer automatic. Could this be the year an MLS team can call itself the continent's champion for the first time since the CCL became a full-fledged continental competition?

3. The Olympic effect

In 2011, the CONCACAF Gold Cup had a significant impact on Major League Soccer, with clubs like the Red Bulls having to make do without five regular starters for as long as a month. MLS has finally adjusted its schedule to respect the international match calendar, but this summer's Olympics -- plus the corresponding qualifying tournament in late March and early April -- could still throw a wrench into teams' plans, as well over a dozen MLS players are in the running to make the Olympic squad.

By the estimation of Peter Nowak, whose Philadelphia Union stands to lose up to five starters to the Summer Games, a player involved in both qualifiers and the main tournament and all the accompanying training camps could miss as many as 17 MLS games -- exactly half the regular season. How will the clubs make up for losing their key players for such a long time? And how will it alter the course of the regular season?

4. Brace yourselves for the Montreal Impact

Since Toronto FC joined Major League Soccer in 2007, each successive round of expansion has been a smashing success and threatened to upstage the last -- the Sounders in 2009, the Union in 2010, the Vancouver Whitecaps and Portland Timbers in 2011. All of which puts tremendous pressure on 2012 newbies Montreal Impact.

The league's 19th team will have the requisite state-of-the-art soccer-specific stadium once Saputo Stadium reopens at some point in the season, and appears to have a strong fan base. Longtime MLS player (but first-time coach) Jesse Marsch seems to have constructed his squad deftly. But will the Impact live up to the hype? Will they be competitive? Or will this be the expansion that backfires on the league?

5. The unbalanced schedule -- and the imbalance in general

By now, clubs know that travel is the bane of the MLS experience. For years, the amount of hours spent in airports or on planes has been brutal for the league's teams, which are spread wide from Vancouver to Washington, D.C. and from New England to Los Angeles.

To alleviate this effect, and to increase the number of games between local rivals, MLS is going back to the unbalanced schedule, making teams play more games within their conference than outside it. Yet this will have a knock-on effect for the entire league. The Western Conference has been stronger than the Eastern for several years now, and this offseason this imbalance has become more pronounced as most Western teams appear to only have gotten stronger while the East largely stagnated. Will this create two distinct tiers within the league? Will Eastern teams struggle when they face their Western counterparts? And will the Western teams be exhausted by the time they get to the playoffs?

Leander Schaerlaeckens is a soccer writer for ESPN.com. He can be reached at leander.espn@gmail.com. Follow him on Twitter @LeanderESPN.