Moreno moved to Anfield from Sevilla in the summer of 2014 but, despite being given plenty of game time over his first two seasons, he failed to live up to the hype.
The 25-year-old fell down the pecking order last term and made only 18 appearances in all competitions while James Miller filled in at left-back.
However he has returned a much-improved player this campaign and Klopp believes the way that the defender coped with being benched last season proved that he has the mental strength to succeed.
"I never had something like this, I never had it to be honest," he told the club’s official website. "This season is not a surprise, the surprise is how he dealt with last season. There was not one bad word in the whole season.
"Yes, he was in my office, yes, he asked what he could do better, and we spoke about the things he had to do better."
Moreno is likely to line up for the Reds when they face his former club Sevilla in the Champions League on Tuesday and punters looking to use a free bet might fancy Liverpool to come away with all three points from the club fifth in La Liga.
The Merseysiders' next Premier League test will be to welcome champions Chelsea on Saturday.