Pitino told Harrell he needed to step up his game, work harder to refine his skills and become the players everybody expected in the preseason.
"I said there's nothing wrong with you try and work on your jump shot, but you can't work on that until you refine your low post footwork," Pitino recalled. "He's worked really hard since then on all aspects of his game.
"He's working hard and you can tell."
The 6-foot-8 Harrell said he's putting in some extra time and it's paying off on the floor with improved play.
Harrell has four double-figured in the past five games for the Cardinals, four of which were victories. U of L will host Cincinnati on Thursday night.
" I just keep working hard," Harrell said. "It's just about my mindset and about getting reps. I just have to keep doing it over and over again."
Harrell started to turn the corner with 14 points and 11 rebounds in 37 minutes in the loss to Memphis before 12 points and 13 rebounds against SMU.
In a win over Houston, Harrell only played 21 minutes and had seven points and four rebounds but he was dominant with 18 points and 13 rebounds on 8 of 10 shooting in a road win at Connecticut. He also had 14 points and 10 rebounds last week in the blowout win over South Florida.
"Montrezl is a hard working guy," junior Wayne Blackshear said. "He works on things a lot and it's been working on the court with him.
"He's really been working on his game a lot."
Harrell has seen has averages jump to 12.1 points and 8.5 rebounds a game and Pitino believes it will get better because "he's really, really working hard."
"I'm not finished and I am still working," Harrell said. "Coach just tells me I have a good jump shot, I just have to keep getting reps and working on it.
"I just want to take what's give to me and not over do it."