The biggest moment of the game came when Lionel Messi had a goal disallowed despite the ball crossing the line.
While he admitted that he couldn't see if the ball had gone over the line or not from the dugout, he suggested that the majority of fans at the Mestalla knew it should have counted.
"From my position it wasn't possible to see if the ball had gone in," said Valverde.
"I saw [Messi] celebrating.
"There were 40,000 people who saw it was a goal.
"It is absurd that the referee didn't see something so clear in a match as important as this one was.
"Every year there are incidents like this and they could turn out to be decisive.
"It seems absurd to me that we don't use technology.
"I guess that we'll have Hark-Eye one day.
"Overall, the level is refereeing in Spain is good and it's difficult to referee.
"I wouldn't be one."
"Everyone has the right to complain," he told the reporters in attendance.