"If you have a bunch of cylinders, we're not running on all cylinders right now," he said during a Q&A; session Sunday morning, before the Lakers fell to 15-18 with a 112-105 loss to the Denver Nuggets on Sunday night.
"I think Pau continues to struggle to figure out how he's going to play with his group," Kupchak said. "Our coaches are struggling as well. We're not going to succeed as a team until we figure that out."
Kupchak also noted the Lakers' need to improve defensively.
"The players that we have on this team are certainly capable of playing lock-down defense," he said. "Everybody has to look at the defense . . . just like the offensive side of the ball. Most guys really, really want to score. In order to be a good defensive team, everybody has to really, really want to play defense and defend."
While Kupchak acknowledged that D'Antoni didn't get a training camp with the roster, he said it wasn't an excuse for a team that should be playing better basketball.
"If everybody buys in, everybody is committed and everybody works as hard . . . on defense as they do on offense, we can be an excellent defensive team going into second half of the year and the playoffs," he said.
Kupchak said a Lakers roster with an average age of 28.5 was not too old.
"I don't think age is a factor, no. That's an excuse," he said. "I don't think that's a factor at all when you look at our team. Young teams don't win championships. You have to have a good mix of experience and some legs in this business. . . . I don't think for a second this team is too old to win a championship."
"I believe Kobe just turned 34 and [in August] he's probably as efficient as I've ever seen him. His shooting percentage is way up," Kupchak said. "We're hoping that we can get on a roll, offensively get more players involved [so] Kobe can do less and play less minutes."
Kupchak didn't address any potential roster changes but if the Lakers continue to struggle, it's worth noting the trade deadline is Feb. 21.
Reserve guard Chris Duhon returned from a two-game absence because of back spasms. He was scoreless with five assists in 12 minutes Sunday. . . . Reserve forward Antawn Jamison played only four minutes, scoring two points. He has played seven minutes in the last eight games.
Pincus is a Times correspondent. Times staff writer Mike Bresnahan contributed to this report.