Can the Blazers keep Damian Lillard and C.J. McCollum together and be a true contender? (David Zalubowski/AP Photo)

OAKLAND, Calif. – It wasn’t long ago that the Portland Trail Blazers looked like a team on the rise, sporting three straight playoff trips and, with Damian Lillard and C.J. McCollum, sporting one of the NBA’s most entertaining and explosive backcourts. In fact, that time was as recently as two months ago, when the regular season began and Portland was widely expected to be back in the middle of the Western Conference playoff picture, as it was the previous season.

So a difficult start to the season, one that has the Trail Blazers currently sitting at 15-22 after a 125-117 loss to the Golden State Warriors Wednesday night here at Oracle Arena, shouldn’t doom the Pacific Northwest to a season of anguish. Even after those struggles, Portland still woke up Thursday only one game behind the Sacramento Kings for the eighth and final playoff spot in the West, and among the teams fighting for the West’s bottom spots the Trail Blazers still seem like the best bet.

“We’ve got time, obviously,” McCollum said. “We’re not where we want to be, and we haven’t played to the level I think we’re capable of. But it’s a really long season with highs and lows and injuries, other stuff that can deter you.”

But whether Portland manages to get into the postseason for a fourth straight year or not, the Trail Blazers’ roster appears more or less locked in the foreseeable future. After handing out a four-year, $72 million contract to sign swingman Evan Turner, committing another combined $156 million over the next four seasons to re-sign restricted free agents Allen Crabbe, Meyers Leonard and Maurice Harkless and then giving McCollum a four-year, $106 million extension that begins next season, Portland is already looking at a payroll of roughly $130 million next season.

Considering that number is only for the 11 players currently under contract, and doesn’t factor in the salary of starting center Mason Plumlee, who will be a restricted free agent this summer and will need to be retained, it’s a virtual certainty the Trail Blazers are going to be well into the luxury tax next season. And while owner Paul Allen, the co-founder of Microsoft, has more than enough money to front those costs, paying significant luxury tax bills for a team that appears to lack elite upside is an uncommon practice in the NBA.

That’s why some around the league have wondered whether Portland, at some point, will have to move on from one of their elite guards.

Because of where the Blazers played Wednesday night, it’s not hard to see the similarities in a problem the Warriors once faced when choosing between Stephen Curry and Monta Ellis in 2012. Now, let’s be clear about something: both Lillard and McCollum are significantly better players now than Ellis was, a diminutive gunner who is a career 31 percent three-point shooter. And there are no chemistry issues to speak of, either, which also is an important thing to consider.

But there is one important — and relevant — similarity: playing both Curry and Ellis together simply left Golden State with too many defensive issues to be a successful team. And swapping out Ellis for Andrew Bogut, a defensive anchor at center, was the first step the Warriors took toward building the foundation at both ends of the floor that has turned the Warriors into a juggernaut.

The Trail Blazers are nothing close to that at the moment, currently ranking 29th in the NBA by allowing 109.9 points per 100 possessions, per NBA.com. Despite the boost in scoring and pace of play around the league this season, defense still matters. The Sacramento Kings — currently tied for 25th in points allowed per 100 possessions — are the NBA’s only team currently in playoff position but outside the top 18. The most analogous team, in terms of what the Trail Blazers are trying to do, is the Houston Rockets who rank 15th.

Trying to build a defensive team around a defensively deficient pairing of Lillard and McCollum requires more intensity from the other positions on the court. And that, in many ways, was the biggest problem with the way the summer played out for Portland.

Portland desperately needed to find an interior defender to help shore up a unit that ranked 20th in the NBA last season, compared to what was the seventh-best offense in the league. But the only big the Trail Blazers wound up signing this summer was Festus Ezeli on what essentially was a one-year flyer.

The reason Ezeli – an excellent fit on paper, given his size and shot-blocking ability – was so cheap, though, was because of a history of knee issues. And, it turns out, those same issues will prevent Ezeli from playing in a single game this season. While Plumlee is a quality player – and particularly skilled as a passing big, averaging 4.2 assists per game and working nicely as a pick-and-roll partner for either player – he isn’t a defensive presence.

Meanwhile, none of the other players Portland spent big on solved that problem, with the most glaring example being Evan Turner. Brought in to be another ball-handler to lighten the load from Lillard and McCollum, Turner has struggled mightily to fit in, with the team’s defense getting even worse while the offense goes from terrific to terrible (113.2 points per 100 possessions compared to 100.4) when he’s on the court.

The lack of a defensive presence inside, combined with the team’s best overall defender, forward Al-Farouq Aminu, missing 18 games due to injury, has seen Portland plummet in defensive efficiency season – a level too low for the Blazers’ still potent offense (currently ninth) to mitigate. Part of that is undoubtedly because of Aminu’s absence, as when he’s been on the court Portland has been roughly league-average defensively.

“It’s still a long season,” Portland coach Terry Stotts said. “We’re still not halfway through. I think it’s encouraging more so the fact that the last few games we’ve played better defensively. Tonight, we competed with one of the top two teams in the league. Regardless of the standings, I’m more concerned about how we’re playing.”

The difficult part of this for Portland general manager Neil Olshey is where to go from here. Players like Lillard and McCollum don’t come along every day — and neither do the kind of big men the Trail Blazers are lacking. Sacramento Kings center DeMarcus Cousins, for example, is lusted after by every fan base with trade assets. But with the new collective bargaining agreement giving him every reason to sign a gigantic five-year contract extension with Sacramento after this season, and with the Kings hoping to finally make it back into the playoffs for the first time in a decade, Cousins is nowhere near the open market. The kinds of bigs that are more readily discussed on the trade market — Brooklyn Nets center Brook Lopez and Milwaukee Bucks center Greg Monroe, for example — come with their own defensive deficiencies.

It makes for a tricky situation moving forward for the Trail Blazers. Many teams would be happy to have a duo like Lillard and McCollum leading their team, a pair of dynamic scorers and fun personalities to which any fan base would gravitate. But whether that combination can be the foundation of a Western Conference contender remains very much up for debate.