Jim Bentley said his side made life too easy for Lancashire rivals Accrington on Friday night.
Morecambe are still looking for their first Football League win over struggling Stanley after a 2-0 defeat which left the Shrimps boss extremely frustrated.
He said: “I’m devastated.
“I think up until the first goal we were probably the better side without creating much.
“But goals change games. It’s disappointing because we’ve given away a silly foul and invited the pressure.
“It’s been our Achilles heel. Teams don’t have to work hard enough to score against us and that was the case tonight.
“The second goal, which is the killer goal, was absolutely schoolboy defending.
“It’s cost us this season. There wasn’t much between the two teams but they’ve come away 2-0 winners because they’ve put the ball in the back of the net.”
Bentley conceded that relegation-threatened Stanley ultimately wanted the points more, which he branded unacceptable.
He said: “We huffed and puffed but we didn’t do enough to win the game.
“And over the whole 90 minutes they wanted it more than us, which is disappointing.
“It wasn’t acceptable, it was a poor performance by us.”