McLellan has been fooled by the Sharks too many times this season.
"The motivation can't be external, it has to be internal in our locker room," McLellan said. "Until we get that, until we make that decision -- and I've said that over and over and over again -- we'll continue to play the way we're playing.
"I don't know when the light is going to go on. They prove to each other on alternating game nights that they can do it."
The Sharks have alternated winning and losing for eight games. Their latest win moved them out of last place in the Pacific Division.
"They got a good team, I don't think anyone questions that," Detroit coach Mike Babcock said. "The big thing is, your ups got to be a lot longer than your downs."
Tomas Holmstrom and Johan Franzen each had go-ahead goals in the first period, but the Red Wings couldn't hold either lead. Joe Thornton made it 1-all late in the first and Dany Heatley gave San Jose a two-goal lead late in the second.
Couture sealed the victory in the third with his second goal.
"We were good for 20 minutes," Babcock said. "The team that worked the hardest and played the hardest won."
"You can't turn over pucks and lose battles and be successful."
"We didn't help the goaltender out," Babcock said.
Detroit lost its previous game in overtime after winning four straight and nine of 11. Its only other loss in regulation at home was Oct. 28 against the Phoenix Coyotes.
"Even though our record is still good, it's still disappointing," Detroit captain Nicklas Lidstrom said.
It looked as though Detroit might roll to another win when Holmstrom was perched in front of the net and redirected Lidstrom's shot into the net during a power play 7:48 into the game.
"I was very disappointed in our group," McLellan said. "The first 10 or 11 minutes, we obviously didn't understand what we were coming into and how good the red and white team has been playing and how good they are at home."
Thornton had scored only once in 15 games and had been held to one shot in three of four games before he put in a short-handed goal during on an odd-man rush with 4:01 left in the first. He was set up by a cross-ice pass from Heatley.
Franzen finished a play in which each of Detroit's five skaters touched the puck. The power-play goal put Detroit ahead 2-1 with 85 seconds remaining in the first.
San Jose snatched the momentum when Wallin and Couture scored 8 seconds apart about 5 minutes into the second period. Heatley made it 4-2 with 1:03 remaining in the second, and Couture ended any comeback hopes for Detroit when his 12th goal gave the Sharks a 5-2 edge with 8:43 left in the game.
"We came out firing in the second and third periods," Thornton said.
The five goals matched a team record at Detroit, tying the total San Jose had in the opening game of the 1994 playoffs when the Sharks advanced for the first time in franchise history.
San Jose improved to 11-0-1 when leading after two periods. Detroit fell to 0-9-1 when trailing entering the third. ... Detroit F Kris Draper, who has played only once this season, was a healthy scratch. ... Detroit won 5-3 on Nov. 30 at San Jose in the teams' first meeting since the Sharks eliminated the Red Wings in Game 5 of the second round of the playoffs.