It's Opening Day around the majors, which means the return of the greatest sport on Earth. (Sorry, ski ballet.) Here are seven big storylines to follow as the 2015 MLB season gets underway.

Can the Nationals keep it 100?
No team has won 100+ games for three years straight, the longest such drought since the 162-game schedule began in 1961. The Nationals stand to end that drought this year thanks to the game's best pitching staff and a deep, loaded lineup.

Washington had baseball's best rotation last year, per wins above replacement. Then they gave a silo of cash to free agency's best starter, Max Scherzer, allowing them to move a guy who had last year's 16th-best ERA among all qualified starters, Tanner Roark, to the bullpen. So yeah, depth.

A schedule packed with games against the divisional doormat Phillies and rebuilding Braves should help Washington coast to the playoffs. So should a full season of Bryce Harper — the 22-year-old phenom who, despite constant "bust!" claims, amassed more WAR through his season as a 21-year-old than all but three players in history. (Fun fact: Entering his fourth season, Harper has yet to face a pitcher younger than him.)

Will young Cubs grow up?

(Rich Pilling/Getty Images)

The Cubs are a popular breakout pick this season, and for good reason. Chicago greatly underperformed last year, grading out as roughly a .500 team. Then they signed a dominant ace in Jon Lester, pried the game's best manager, Joe Maddon, away from Tampa Bay, and made a flurry of smaller moves to remedy last year's weaknesses.

Chicago also has a host of solid young talent approaching their prime years and oodles of top prospects waiting in the wings — including dinger factory Kris Bryant, who should get called up within weeks. Plus, Hollywood never lies, and Back to the Future II predicted the Cubs would break their near-century-long curse with a World Series title in 2015.

Parity in the USA
All but a handful of teams believe they can win the World Series this year — and they're not wrong. Increased revenue sharing, a competitive balance tax, and, most importantly, the introduction of a second wild card have made it easier than ever for any team to go the distance. Take last year, when the World Series for the first time ever featured two teams that failed to win 90 games over a full season.

All but five teams made win-now moves this winter, according to USA Today. They include the Blue Jays, whose 21-year playoff drought is the majors' longest; the White Sox, which lost 188 games over the past two seasons and then overhauled the roster in a single manic week; and the Padres, which, after posting MLB's worst team batting average since 1969, moved or acquired 29 players in a two-week span and emerged with a brand new outfield featuring two former All-Stars and one ex-Rookie of the Year. As a result, the preseason projections show a smaller gap between the top and bottom of the pack than at any point in at least the last decade, with a huge cluster of playoff hopefuls in the middle.

The Old York Yankees
New York fielded the oldest lineup in baseball last season, and their biggest offseason addition was 30-year-old third baseman Chase Headley. As happened last year, the ravages of time could again blow this team up with injuries.

If everyone stays healthy, New York could sneak into the playoffs. That's not likely. Baseball Prospectus projects the Yankees to finish fourth in the AL East with a sub-.500 record, and other projections aren't much kinder. A third-straight season with no October baseball could be all the more miserable for Yankees fans given…

The return of Alex Rodriguez

(Jonathan Daniel/Getty Images)

Yes, the most hated player on the planet is back after an unprecedented suspension for PED use. A-Rod's performance has plummeted since the crumbling slugger won the AL MVP award in 2007, and there's no telling how the 39-year-old will fare after missing more than a year of baseball. Oh, and he's still owed $64 million over three years, plus millions more if he hits a few milestones.

Though there's a compelling reason for everyone to root for A-Rod, Yankee Stadium is a hostile wasteland where fans will call for his head after each whiff. It could be a long season in New York.

Will anyone score runs?
They will! They just probably won't score very many of them.

Driven primarily by an influx of power pitchers and an expanded strike zone, team scoring last season fell to an average of 4.07 runs per game, the lowest mark since 1981. Meanwhile, strikeouts spiked to 7.7 batters per game, the highest rate ever.

The league has reportedly considered shrinking the strike zone to boost offense — but not until 2016. Unless that happens, expect the league-wide offensive woes to continue.

New pace of play rulezzz...
The average game in 2014 lasted a record three hours and two minutes — up from an average of two hours and thirty minutes in the 1970s. So concerned that bored fans will ditch the sport, MLB is rolling out a handful of measures this year aimed at speeding up games.

Under the rules, hitters must keep one foot in the batter's box during at-bats, while pitching changes and half-inning breaks will be timed. The tweaks won't have a dramatic impact on game length, but they should whittle some minutes and could lead to more significant changes down the road, like pitch clocks, which the league has tested in the minors.

Parting predictions

American League Divisional Champs
Red Sox, Tigers, Mariners

AL Wild Cards
Angels, Indians

National League Divisional Champs
Nationals, Cardinals, Dodgers

NL Wild Cards
Cubs, Marlins

World Series
Nationals over Mariners

Come on future: Prove me wrong.