The Yellow Submarine put on a valiant second leg performance, coming back from two goals down to draw level.
But they ultimately dropped out of the competition at the penultimate stage after errors from Geronimo Rulli, losing 3-2 on the night and 5-2 on aggregate.
In the second half, the Yellows noticeably lost momentum, failing to keep up their tight press and high energy that suffocated Liverpool in the first half.
Some have questioned whether Emery decided to change approach at half-time, but it seems that was not the case.
Speaking after the game, Emery explained how Villarreal’s press was harmed by Gerard Moreno’s lack of fitness and a collective loss of energy around the pitch, caused by a hugely demanding Liverpool side.
“Today we needed something more,” he admitted.
“Defending strongly and for them not to position themselves. We found the goal, the penalty and they didn’t get close.
“The first half was hopeful. Gerard Moreno had discomfort again, but it was difficult for him to sprint and we lost strength.
“We weren’t the same anymore. We needed to have more of the ball, but their goal made too many demands on us mentally.
“We’ve run out of energy. Without the ability to respond to the demands of a tie against Liverpool.”