Do Mariners finally have the depth to make playoffs?

This time, the Mariners aren’t trying to balance all this hope atop a flimsy base.

Unlike in 2008 and 2010, when they flopped and lost 101 games following winning seasons, they appear more prepared to build upon success. The difference? First, the franchise has spent nearly seven years trusting general manager Jack Zduriencik’s rebuilding plan, the longest it has believed in something in quite a while. And second, after the Mariners’ latest breakthrough, they were more diligent this offseason in trying to turn an 87-75 overachiever in 2014 into a true playoff roster.

They didn’t just stop at making a big splash. They filled their biggest need by signing cleanup hitter Nelson Cruz, a three-time All-Star who led the majors with 40 home runs last season, to a four-year, $57 million contract. But they’ve done that before. Remember the blockbuster trades for Erik Bedard and Cliff Lee? Those weren’t supported by enough sound, lower-profile decisions to sustain a winner.

This time, the Mariners didn’t just nab a headliner and ignore other issues. Zduriencik made his best attempt at creating a roster with the depth and attention to detail to thrive for 162 games.

Did he do a good enough job? The Mariners’ postseason hopes might depend on the answer.

You love the Mariners for their star power, and certainly, they need Felix Hernandez, Robinson Cano, Kyle Seager, Fernando Rodney, Hisashi Iwakuma and Cruz to be at their best or close to it. But the unknown — and how well the Mariners prepared for it — will be the difference between falling one game short of the postseason and actually making it.

Will Seth Smith and Justin Ruggiano combine to give the Mariners suitable production in right field?

Will veteran lefty J.A. Happ eat quality innings and improve the depth of a starting rotation that will rely on a few prodigies whose innings must be monitored?

Can a bench that includes utility players Rickie Weeks and Willie Bloomquist produce in the event of injury or poor performance? Will the seven pitchers in the bullpen be lights out again, and do they have a closer contingency if the 38-year-old, always-living-on-the-edge Rodney can’t duplicate his record-setting 2014 season? Will shortstop Brad Miller take control of that job in the absence of Chris Taylor, who’s out because of a broken wrist?

The good news is that throughout the entire 40-man roster — not only the 25 players who make the team — the Mariners have the potential to handle in-season misfortune. After last season, when starting pitching attrition and a lack of outfield depth cost the Mariners, Zduriencik made it a priority to put together a more complete roster. After signing Cano to a $240 million deal last year, ownership continued to spend. You can’t fault the Mariners’ commitment. Soon, you’ll learn if they have the judgment to go with it.

Since taking over after the 2008 disaster, Zduriencik has had his struggles acquiring the proper veterans to help the Mariners move forward. He has had one big-money bust in Chone Figgins. Several of his stopgap ideas, such as Corey Hart last season, haven’t worked out. But with a larger payroll, he was afforded better options in building the 2015 ballclub. The Mariners also aren’t as needy as they were before, when they would take crazy chances looking for a quick fix while they replenished the farm system.

This is now a Mariners team that is utilizing every franchise-building resource. They have spent huge money in free agency. Their first wave of homegrown players has arrived, with some thriving (Seager), some ready to emerge (James Paxton, Taijuan Walker) and some still in question (Dustin Ackley). The Mariners have made decent trades, such as the deal to acquire Logan Morrison, and they have the farm system to make a big, midseason deal if necessary. They’re finally functioning like a normal big-league club, not a rebuilding outfit.

But what happens when they lose a player they’re depending on this season? Do they fall apart while that guy is on the disabled list? Or can they manage?

This is how we’ll know how good they really are.

After years of having thin rosters, Zduriencik had the payroll and the latitude to make something special. With three All-Stars now in the middle of the lineup, the Mariners’ offense shouldn’t be pathetic anymore. The pitching looks solid. The bench is better than previous Mariner benches. It’s easy to see why the Mariners have become such a popular pick to make the playoffs.

What could go wrong?

In a marathon season, what could not go wrong?

For that reason, the Mariners did much more than purchase the Boomstick this offseason. Smith, Ruggiano, Weeks and Happ were part of a plan to make this team deeper and more resilient.

You can appreciate the thoroughness of their effort, for a change.

Whether they were effective is the most important — and difficult to answer — question.