DENVER — The Denver Nuggets already told us their roster isn’t good enough this year, firing their general manager on the eve of the postseason.

The biggest issue with the roster Calvin Booth constructed? Depth. It was the main culprit in the Nuggets’ pivotal Game 4 92-87 loss to Oklahoma City on Sunday, which evened the series at 2-2 and took home-court advantage back to the NBA’s top-seeded Thunder.

With about 38 hours to turn around after a grueling Game 3 overtime win, the Thunder made a concerted effort to go deeper into their roster. Both in-game and leading up to it, the fact that the Thunder could play more guys impacted the Nuggets as they tried to back OKC into the corner.

“With a quick turnaround with an early game today, we made a very intentional effort to use our depth today and get everybody going,” OKC head coach Mark Daigneault said.

Just over five minutes into the first quarter, MVP front-runner Shai Gilgeous-Alexander was already on the bench getting rest. Meanwhile, Nikola Jokic played the entire first period, which his team scored just eight points — the fewest ever in a playoff quarter in franchise history.

Jokic has been taxed all season, and so has Jamal Murray — who played a season-high 48 minutes in Game 3. The Nuggets had to keep hoping their two-man pairing would be enough.

“I think both teams were very tired coming off an unbelievably physical overtime battle on a late Friday night. So it affected us, but it surely affected them as well,” Nuggets interim head coach David Adelman said. “Both of us had super tired legs, so it was about who’s going to make that final run.”

The Nuggets rebounded from their brutal first quarter thanks to a 3-point barrage in the third quarter, during which the team hit seven from distance. It pushed the Nuggets to an early fourth-quarter lead of eight. But when it was closing time, where Jokic usually thrives, the Nuggets had nothing.

“I thought we were making the push. To their credit, they were the ones to make the final run, and we made mistakes late,” Adelman said. “We can call them mental mistakes, physical, whatever it was, we didn’t play well enough the last six minutes to win a playoff game.”

The Thunder out-scored the Nuggets 29-16 down the stretch, handing Denver its first tight loss of the postseason. The most important part of the game was when OKC got a jolt from Aaron Wiggins and Cason Wallace early in the fourth to spark the comeback. Each bench player hit three triples. That bench scoring, going 35-8 against the Nuggets, was a separator. While the Thunder played nine guys for at least 12 minutes, the Nuggets only had seven players hit a shot.

“We were very tired, as were they — and we got to take a look (back) at the whole roster of guys that can help you and give you a couple of minutes of energy,” Adelman said. “We’ve ridden our guys throughout the season, for good reason. It’s an amazing starting five, but I’ve got to try to be as creative as I can be to help them have some legs like in the game.”

The Nuggets’ starting five outscored the Thunder 41-26 in the 19 minutes they played together. But they were beaten both in the first and fourth quarters.

Denver’s key players didn’t have the legs to start the game.

The Nuggets’ lack of bench meant there was nobody to take pressure off during the game.

And Denver’s key players then didn’t have the legs to end the game.

Where the Thunder played 11 guys over 700 minutes this season, the Nuggets only utilized eight that way. While OKC got the rest going into the playoffs and after sweeping Memphis, Denver has been battling almost every night for a month to first make the playoffs, then get past Los Angeles.

The Nuggets shot just 31%, 24% from deep, and even missed some big free throws late despite living at the line early — some key indicators of fitness.

Everything changed because the Nuggets don’t have enough playable bodies. And it’s put pressure on their key players all year. And how the Thunder came roaring back probably galvanized a young group that was on the brink themselves.

All of those come on the heels of last year’s Round 2 Game 7 exit,where everyone said fatigue did the Nuggets in — pointing at Booth’s failure to adjust from last year’s issues.

Game 5 is Tuesday in Oklahoma City. The Nuggets went from being 11 minutes away from going up 3-1, a spot NBA teams are 192-9 since 1984 — to even at 2-2 while having to win another road game.

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