Manager Marco Silva said his Everton side were “too anxious” and “too nervous” as they slumped to a fourth loss in five Premier League games with defeat against Leicester.
Jamie Vardy scored the only goal of an error-strewn encounter during which the Toffees rarely roused their supporters inside Goodison Park.
“It was a strange afternoon for us,” Silva said. “It was a disappointing result and not a good performance.
“We wanted to give good feelings to our fans and we didn’t achieve that.
“This afternoon, even the simple pass went two metres wrong. When you do that it is impossible to get the creativity and the mobility to create chances to score.
“We didn’t create much in the first half. But every time we won the ball in the good positions it wasn’t good enough. A lot of easy mistakes and missing easy passes.”
Vardy’s 58th-minute goal was one of the few highlights of a turgid affair.
Full-back Ricardo Pereira capitalised on defender Michael Keane’s error to play in the England striker, who finished with an angled drive past Jordan Pickford.
Everton were not much of a force in attack, with Jonjoe Kenny’s first-half shot off the bar the closest they came to scoring.
The Toffees, who have now not won in their past four home games, remain 10th in the table, while Leicester move above Wolves into seventh place.
Everton spent more than £200m on players in two summer transfer windows, but some fans will be wondering where their quality signings have been hiding in recent games.
A 5-1 win at Burnley was the only highlight of a rotten festive period in which they have conceded 12 goals in five games and failed to score in their past two.
Leicester keeper Kasper Schmeichel was tested only twice, by substitute Cenk Tosun on both occasions. The first was a firm 20-yard strike which he punched clear before the Dane reacted to push away a close-range header late on.
It was a mistake by £30m signing Michael Keane, who failed to control a Leicester long ball, which resulted in the decisive goal.
He and the rest of the Everton players will hope to avoid another slip-up when they host League Two side Lincoln City in the FA Cup third round on Saturday.
In contrast to Silva, Leicester manager Claude Puel has had a wonderful festive period.
That is now three wins in four games for the Foxes, with those victories coming against Chelsea, Manchester City and Everton.
Those were the type of sides the Foxes were beating during their title-winning season in 2015-16.
They lack the consistency of that campaign and have lost some key players since, but one standout act from that season has remained and he once again made the difference.
Vardy had only one shot on target in the match, but he made it count. It was one of his typical finishes, running on to a through ball before striking home left-footed from an angle.
The first 15 minutes of a forgettable first half were farcical. Two teams, laden with millions of pounds of talent, could barely hold on to possession for more than a few seconds.