Despite having long since locked up the No. 1 seed in the Western Conference and home-court advantage throughout the 2018 NBA playoffs, the Houston Rockets have mostly continued to play their best players down the stretch, with reigning Coach of the Year Mike D’Antoni preferring to keep his key contributors in rhythm in hopes of entering the postseason this weekend in top form. That approach came back to bite him on Tuesday against the Los Angeles Lakers — a game in which Houston had nothing to gain, and may have lost defensive stalwart Luc Mbah a Moute.

With just over seven minutes to go in the second quarter and the score tied at 32, Mbah a Moute set a ball screen for Rockets star James Harden and then rolled to the basket. Harden set him up with a bounce pass in stride, and Mbah a Moute sliced to the rim, where he was met by Lakers center Thomas Bryant. Mbah a Moute powered through the defender, throwing down a right-handed tomahawk dunk … but immediately stiffened up upon landing and reached for his upper right arm, a very bad sign for a player who earlier this season missed a month after suffering a dislocated right shoulder.

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As soon as they regained possession, the Rockets called timeout. By that time, Mbah a Moute was already on his way to the locker room to get checked out. Shortly thereafter, Houston confirmed the fears:

After the Rockets finished off a 105-99 win, D’Antoni sounded an optimistic note, but didn’t have much in the way of a concrete update to offer:

After that MRI, it remains unclear when the Rockets might be able to expect Mbah a Moute back on the court … but according to ESPN’s Adrian Wojnarowski, it probably won’t be for at least a couple of weeks.

You’d be forgiven if Mbah a Moute’s not the first name you think of when you think about the Rockets. On a team led by the league’s likely MVP in Harden and a nine-time All-Star in point guard Chris Paul, a 10-year vet who’s averaged 6.4 points and 4.1 rebounds per game in his career doesn’t necessarily constitute demand much headline space. But the 31-year-old from Cameroon’s a vital defensive cog for a Rockets team that, while known for its offense, ranks sixth in the NBA in points allowed per possession.

Mbah a Moute primarily comes off the bench for Houston, with only 15 starts in his 69 appearances this season. In the short term, the Rockets’ sheer array of offensive talent ought to help them withstand his absence should he miss the opening round of the playoffs, and maybe longer. But quiet as it’s kept, the journeyman who’s played for six teams in the last six seasons has been one of the most versatile defenders in the NBA this year:

At 6-foot-8 with a 7-foot wingspan, tremendous defensive instincts, a veteran’s savvy about where to be on the floor, and the strength to play up a spot in the lineup against bigger power forwards, Mbah a Moute has been an integral piece of a Rockets defense that’s worked all season long on switching assignments against opponents who like to play small, run defenders through screens, and try to muck up schemes with crossmatches. Like, for example, the Golden State Warriors, the defending NBA champion the Rockets have been constructed to dethrone.

Mbah a Moute was pretty great against the Warriors this year. He averaged 14 points and four rebounds in 28 minutes per game in his two appearances against Golden State during the regular season, shooting 10-for-15 from the field and 4-for-7 from 3-point range. Houston outscored the Dubs by 17 points in Mbah a Moute’s 56 minutes against them this season. And Golden State’s one win over the Rockets came back in January, while — you guessed it — Mbah a Moute was sidelined by his first right shoulder injury of the season.

The Rockets have allowed just 101.1 points per 100 possessions with Mbah a Moute on the floor this season, compared to 105.8 points-per-100 when he sits, according to NBA.com’s lineup data. Over the course of the full season, that’d be equivalent to the difference between posting the NBA’s No. 1 defense and its No. 15 unit; nowhere is the gap between excellent and average more glaring than in the postseason.

When Mbah a Moute has shared the floor with P.J. Tucker, another versatile and bruising defense-first forward, Houston has absolutely blown opponents’ doors off, outscoring them by 19.5 points-per-100 in nearly 900 minutes, according to NBAwowy.com. And in the 20 games he’s missed this season, the otherwise-stampeding Rockets have gone a comparatively pedestrian 13-7. (Though, to be fair, they’ve only had the trio of Harden, Paul and center Clint Capela for four of those games, and they’ve won them all.)

With Mbah a Moute sidelined, the presence and performance of Trevor Ariza becomes even more important for a Houston team that needs as many two-way answers as possible on the wing. D’Antoni could turn to buyout-deadline addition Joe Johnson for more minutes at the three and four spots. But the eight-time All-Star hasn’t looked like the same difference-maker he was for the Utah Jazz last season since coming to Houston, struggling to approach 40 percent shooting from the field without any of Mbah a Moute’s defensive versatility.

While Ryan Anderson would provide threatening spot-up shooting when he comes back from his ankle sprain, and Gerald Green offers athleticism along with a gift for scoring in bunches, the defensive concerns of relying on them to hold up on switches against elite offensive opposition during the playoffs would loom large. Three-guard lineups featuring Eric Gordon alongside Harden and Paul with Tucker or Ariza and Capela up front could have enough muscle to get the job done against small-ball opponents, but there’s still a downgrade in overall defensive smarts and switchability — which become really, really important the further you get in the postseason.

The Rockets have options for divvying up Mbah a Moute’s 26 minutes a night, but none of them provide quite what the former UCLA standout has for Houston this season. As long as they’ve got Harden, Paul and Capela healthy, they’re still a deserving top seed and a threat to make it all the way to the Finals, regardless of which supporting cast members they’ve got available through the first round or two. But losing Mbah a Moute — or even getting him back in a diminished form after a month on the shelf — hurts in a very particular and damaging context, and they know it.

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Dan Devine is a writer and editor for Yahoo Sports. Have a tip? Email him at devine@oath.com or follow him on Twitter!

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