Clippers’ strong start has continued despite a decline in play of reserves

The Clippers’ 15-6 start has provided coach Doc Rivers precious little to fret over, but the recent underwhelming play from the reserves has gone from blip to trend.

Since outscoring opponents’ benches in 18 consecutive games to open the season, Clippers reserves have been outscored in each of the last three games — by 13 against Portland, three against Phoenix and 15 against Sacramento — and figure heavily in the team’s worst statistical lineups during the last week.

“I thought our second unit tonight didn’t play to their normal standards,” Rivers said Thursday night after a 133-121 victory over the Kings. “Actually that’s been a couple nights in a row, so we’ve got to fix that because for whatever reason they’re not playing great right now.”

That’s a shift from the bench’s production during the season’s first month, when guard Lou Williams and center Montrezl Harrell regularly took over close games in the final minutes and, in the process, inserted themselves into the discussion for the NBA’s sixth man award.

The two continue to rank first and third in the NBA in bench scoring. Harrell boasts the league’s fourth-highest field goal percentage and has scored 10 or more points in 13 consecutive games, but Williams has been uncharacteristically held in check. His 62-game streak of scoring in double figures off the bench ended Sunday in Portland, and he’s made 29.7% of his shots from the field, nine percentage points lower than his season average, during the last three games.

The least effective five-man lineups used against Portland and Phoenix, as gauged by a plus/minus analysis, consisted entirely of reserves. Against Sacramento it included four reserves. Williams, Patrick Beverley and Mike Scott — all of whom have acted as spark plugs for the Clippers at various points this season — were the constants among those lineups. Since being moved to the bench five games ago against Washington, Beverley has produced offensive and defensive ratings comparable to those when he started. He has also shot five percentage points worse on three-pointers.

Even if the reserves haven’t played up to their usual standard, they still lead the league with 53.8 combined points a game and the Clippers remain hot. Entering Sunday’s road matchup with Dallas, Los Angeles has won four consecutive games and remains in first place in the Western Conference.

“They’re not playing bad but they’re just not playing great,” Rivers said of the bench. “That’s something that’s fixable, because it’s one of our better units.”

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When: 4 p.m. PST Sunday

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Update: Mavericks rookie Luka Doncic is questionable to play because of a strained right hip. He has scored 20 or more points in 10 games but made only two of his 13 field-goal attempts Friday in a loss against the Lakers. … Dirk Nowitzki will miss his 21st game to begin this season while still recovering from left ankle surgery. ... Former Clippers center DeAndre Jordan is averaging 11.3 points and 13.2 rebounds, fifth most in the NBA, this season. A career 45.4% free-throw shooter, he has made 77.1% of his foul shots with Dallas.

andrew.greif@latimes.com

Twitter: @andrewgreif