The Clippers have lost eight of their past 10 games, lacking continuity as players have shuffled in and out of the lineup because of injuries and health maintenance. They have had offensive droughts and stretches of turning the ball over too much, trouble on the glass and defensive lapses.
On Tuesday night, the Clippers trailed by 14 in the second quarter, then stormed back to take a four-point lead late in the third.
But Philadelphia outscored them 36-13 after that to put the game away.
George said the Clippers have to start showing urgency to find their chemistry and continuity.
"I mean, it's now," George said. "We've just been behind the ball in terms of injuries, lineups, and guys in and out.
"Urgency starts now. We've got to start playing with some desperation."
George scored 13 points and grabbed eight rebounds in 28 minutes in his return from tweaking a right hamstring injury that already had kept him out of seven straight games earlier this season. George said he felt good coming out of Tuesday night's game but will not play in Utah as a precaution.
Leonard, who had 27 points and four rebounds, typically sits out one game of a back-to-back as part of his return program from a torn right ACL that kept him out all of last season.
The Clippers have dealt with injuries all season. This was just the 16th time George and Leonard played together this season. The team is still without guard Luke Kennard (calf) and will not have John Wall (abdomen) for at least another two weeks. And Clippers coach Ty Lue said Reggie Jackson was limited to 13 minutes due to his back tightening up.
"We gotta come in and win these games," Leonard said. "And be focused enough to execute and stay strong with each other. The things you do to win a basketball game is you gotta get the defensive rebounds, we gotta make shots, we can't give the other team the ball, we gotta get back in transition, and those things are hurting us right now."