Baseball has a funny way of convincing us we're certain of something during the offseason, only to laugh in our collective face a few months later.

Last offseason, there was one division we could all predict with relative certainty: The Nationals were a lock in the National League East. Turns out, the Mets had something to say about that.

Last offseason, we all knew the American League West race would be a thriller, with the Angels, A's and Mariners appearing fairly even on paper. Indeed, the race turned out to be a thriller. And -- as projected by nobody -- the Rangers and Astros came away with playoff berths.

The point is: We never really know what we're talking about when it comes to forecasting the upcoming season. But certain clubs baffle us more than others. Before the season has even begun, there are a few teams throwing a wrench in our playoff projections.

Here's one in each division.

AL East: Boston Red Sox

In case you've forgotten, here's a brief rundown of Boston's past four seasons:

• 2012: 69-93, last place
• 2013: 97-65, World Series champs
• 2014: 71-91, last place
• 2015: 78-84, last place

There's no team in baseball with a wider range of expectations than the Red Sox. It wouldn't be particularly surprising if they finished in last place for the third straight year. It also wouldn't be particularly surprising if they won their second World Series in four seasons.

The Red Sox pieced together one of the best offseasons in baseball, adding a bona fide ace in David Price and an elite closer in Craig Kimbrel. Plus, they might have the best collection of young talent in the AL. On paper, that's a recipe for Boston to take a serious leap forward. But weren't we all saying the same thing at this time a year ago?

AL Central: Detroit Tigers

There's no division tougher to project than the AL Central. For the purposes of this exercise, all five teams could fit the bill as "unpredictable." The Royals are back-to-back AL champs, but many statistical analyses have them around the .500 mark. Meanwhile, the Indians, Twins and White Sox each have reason to believe they'll contend -- but they all also have gaping holes in their rosters.

That said, none of those clubs is more enigmatic than the Tigers, who were surprisingly very active this offseason. They needed starting pitching help; they acquired Jordan Zimmermann. They needed an outfielder with some pop; they acquired Justin Upton. They needed a closer; they acquired Francisco Rodriguez.

The Tigers look like a pretty complete team on paper. But they're coming off a last-place finish, and they'll be relying heavily on a core of five players -- Miguel Cabrera, Justin Verlander, Ian Kinsler, Victor Martinez and Anibal Sanchez -- who are all older than 30.

AL West: Seattle Mariners

The Mariners missed the postseason on the final day in 2014 before stumbling to a fourth-place finish in '15. Under new general manager Jerry Dipoto, they've completely remade their roster -- in stark contrast to the rest of the West, which stayed largely stagnant this offseason.

Five players in the Mariners' projected starting lineup were not on the Opening Day roster last season. The bullpen is improved, the middle of the rotation is improved and the outfield is improved -- all much-needed upgrades.

But in a tricky division with two young teams -- the Astros and Rangers -- that are primed for lots of future success, Seattle needs superstar performances from two of the game's most enigmatic superstars, Felix Hernandez and Robinson Cano.

NL East: Miami Marlins

We should know better than to make assumptions about the NL East, given what transpired last season. But the 2016 version of the East looks pretty cut and dry. The Phillies and Braves are rebuilding and probably won't compete. And the Mets and Nats look poised to battle it out for the division title.

Where does that leave Miami? Great question. It could very well fall into either of the two categories. Jose Fernandez is one of the game's best young pitchers, and Giancarlo Stanton is one of its best young hitters. (And at this point, we can probably remove the word "young" from that sentence altogether.)

The Marlins have too many question marks to be mentioned with the Nationals and Mets as division favorites. But they have too much talent to be mentioned with the Phillies and Braves in the cellar. As it stands, 2016 is a crucial swing year for Miami.

NL Central: St. Louis Cardinals

No franchise has been more stable than the Cardinals over the past couple of decades. And yet, entering the 2016 season, they're probably the NL Central's most unpredictable team.

Look, St. Louis will at least be competitive this year. The Cards are going to find themselves in the playoff hunt come August -- as they always are -- but there was some serious roster turnover from the club that won 100 games last season. Jason Heyward and John Lackey left for the division-rival Cubs, and Lance Lynn is out for the season. Meanwhile, Carlos Martinez and Adam Wainwright return from injuries, joining newly signed Mike Leake in the rotation.

It's reasonable to see the Cardinals winning 100-plus games again in 2016, securing a fourth straight Central title with relative ease. It's also reasonable to see the Cubs and Pirates finally catching and passing them. In any other division, the Cards would probably enter the season as favorites. In the vaunted NL Central, they're the biggest question mark.

NL West: Arizona Diamondbacks

The Giants and Dodgers are proven powerhouses and postseason regulars. The Padres and Rockies, meanwhile, both made moves this offseason that indicate they're rebuilding. Four teams in the NL West are easy to peg -- on paper, at least. And then there's Arizona.

No one is denying that the D-backs improved significantly this offseason. They added Zack Greinke, one of the best pitchers in the sport, while simultaneously stealing from a division rival. They also traded for Shelby Miller, who complements a healthy Patrick Corbin behind Greinke in the rotation. The offense is going to score plenty of runs, and the bullpen was mostly solid a year ago.

That said, it's extremely tough at the top of the NL West. The Greinke-less Dodgers are still one of the deepest teams, and the Giants kept most of their World Series-caliber core intact -- while adding Johnny Cueto, Jeff Samardzija and Denard Span.

How difficult is it to build a contender in the West? Just ask the Padres, who occupied this position a year ago. Only time will tell whether the D-backs' moves were the right ones.

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AJ Cassavell is a reporter for MLB.com. Follow him on Twitter @ajcassavell.

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