The Toffees won 3-0 via a double from Beto and a strike through Iliman Ndiaye.
"In terms of the things we’ve spoken about, not gifting goals away, making sure we’re in the game, getting control of the game, it wasn’t there," Rosenior reflected after the game.
"It turned into a really difficult evening where the result and performance were nowhere near what we expected or wanted.
"But then, it feels like out of nowhere, they score. That isn't the first time that’s happened, and what happens if you’re in a difficult run of games is that your energy and confidence levels can drop when the other team scores first. That’s what happened.
"Pickford makes a world-class save at 1-0, then we come out in the second half and have control of the game, but we make a mistake and they’re 2-0 up, which gives them even more energy. It’s about flow and momentum, and we didn’t have that in the game today."
The defeat was a fourth on the bounce, as Rosenior continued: "I don’t think there’s a lack of effort, I don’t think there’s a lack of belief and determination in the team.
"I am aware that when you’re on a run of defeats and performances that we’ve had, those things get levelled at you but I don’t think that’s the issue in this moment."