If you’re a Mariners fan, you have to be wondering.

And rightly so.

When a team wins 86 games and stays in contention for the playoffs until the last few days of the season, your first reaction is to be excited about the 2017 season.

But what if Jerry Dipoto, the general manager who put together that 86-win team and could have kept it pretty much intact, makes 12 trades during the offseason and changes the entire team structure?

Now your excitement turns to being puzzled.

Although Dipoto retained the big bangers from his offense – Robinson Cano, Nelson Cruz and Kyle Seager – along with Felix Hernandez and Hisashi Iwakuma from the top of the rotation - almost everything else has changed.

Dipoto probably figured that if his three-man wrecking crew in the middle of the order could deliver 112 home runs and help the M’s to the third-highest run production in the American League and Seattle still couldn’t reach the playoffs for the 15th consecutive year, he had to change the look of things.

And soon.

The Mariners have morphed into one of the oldest teams in baseball, so their window of potential greatness won’t be open long.

SEAGER IS the only one from that group of five cornerstone players who is under 30, and he’s 29.

Iwakuma (16 wins) and Cruz (43 homers) are coming off spectacular seasons, but they are 38 and 37, respectively. Time catches up to everyone eventually.

Mariner fans know the answer to this question, but you have to wonder how this team with such long-ball production won only 86 games a year ago.

Well, the outfield defense – to the inexperienced eye and by advanced metrics – was simply awful. Leonys Martin in center field was terrific, but the corners were disasters.

The M’s also were almost (26th) the worst base running team in baseball, and arguably the slowest.

Dipoto set out to fix that.

He replaced the corner outfield platoon of Nori Aoki, Franklin Gutierrez and Seth Smith — admittedly a decent offensive group — with former Royals speedster Jarrod Dyson to play left and rookie Mitch Haniger, who will take over in right.

Haniger has had excellent minor league numbers and he’s a decent athlete, but he’s played only 34 games in the majors. He became part of the Mariners’ biggest trade, moving to the Northwest from Arizona along with shortstop Jean Segura for a couple of young and talented disappointments, shortstop Ketel Marte and starter Taijuan Walker.

Snagging Segura, who stole 33 bases last year and led the NL with 203 runs scored, in exchange for two truly gifted kids is the kind of gamble you take when the core of your team is getting long of tooth.

THERE ARE other new question marks, however.

Consider first base, where Seattle got 30 home runs from the combination of Adam Lind and Dae-Hoo Lee.

This time around, the platoon will be veteran third baseman Danny Valencia and rookie Dan Vogelbach, neither of whom is likely to get fans very fired up.

On top of production (or lack of it), Valencia has not been popular in the clubhouse anywhere he’s been — one reason he’s been traded pretty much every year.

And finally, that brings us to the pitching staff.

King Felix had an off year (for him) in 2016, and you wonder about age – he’ll turn 31 the first week of the season – and the toll all those hard-throwing innings may have taken.

The King is coming up on 2,500 career innings, and last season his WHIP shot up from a career 1.18 to 1.32. He was hittable, in other words.

DIPOTO tried to shore up the rotation by acquiring two vets coming off terrible years — Yovani Gallardo and Drew Smyly — plus lighting some candles so that oft-injured James Paxton, a truly gifted lefty, can finally stay healthy.

An under-the-radar deal just last week might make a difference sometime this year: Seattle grabbed Chase de Jong, a right-hander who has been overpowering in the high minors, from the Dodgers.

De Jong could easily wind up in what appears to be a questionable rotation.

The bullpen is deeper but fraught with injuries, and Edwin Diaz must duplicate his rookie stardom as a closer.

Dipoto has rolled the dice, knowing he’s close to the promised land – but won’t remain there much longer.

The Mariners will be more athletic and certainly better defensively, which will help the pitchers.

But so many questions…

They could win 75 or 95, and most people in baseball wouldn’t be shocked at either result.

Steve Cameron is a special assignment reporter for The Press. Reach Steve at scameron@cdapress.com.