Tomas Hertl cut it to 4-3 at 17:54.
"This is not easy, the season we've gone through," San Jose coach David Quinn said. "There's a lot of level of frustration because we feel like we've played better, but our record is what it is. I'm just proud of the way we competed and didn't give up. Even at 4-2, we kept playing and had chances to tie."
Adrian Kempe gave the Kings a 1-0 lead at 5:59 of the first period, positioning himself at the edge the crease and finishing a wraparound pass from Byfield.
Nick Bonino tied it 1-1 at 1:20 of the second period. Copley couldn't catch Erik Karlsson's slap shot from the left point, and as the goalie tried to poke the rebound away, Bonino scored five-hole with a backhand.
"We're there every game and just can't get wins," Bonino said. "It's frustrating for everyone. We're trying everything in practice and video, competing, and it's just not going our way right now."
Byfield scored his first goal of the season for the Kings in 16 games to make it 2-1 at 6:58, redirecting Mikey Anderson's shot from the point five-hole on Reimer.
"It was good to see him get rewarded around the net. Maybe that will give him some offensive confidence," McLellan said. "He's had some looks since going up on the wing and it hasn't gone in for him, and you could sense a bit of frustration."