Johnson's second half subsitute appearance, his first since December 28th, was the only plus point of a dismal night.
"It was the only positive, to have another body and another player.
"He can be an important player for us for the rest of the season," said Benitez.
"It was clear he still hasn't got the match fitness but at least he showed his quality.
"He was going forward and it's a different option in the side."