Ellis and Reece Conca were singled out by Hardwick after the Tigers' round one loss to Gold Coast as second-tier midfielders who "didn't stand up".
In Thursday night's 12-point win over Carlton, Ellis was tasked with running with elite Blues' midfielder Bryce Gibbs while Conca was on captain Marc Murphy.
After keeping Gibbs to 12 possessions, Ellis said he felt he had earned back some respect, highlighted when Hardwick walked past him in the rooms post-match and gave him a proud thump on the back.
"It's probably the longest 13 days I've had to wait to try and rectify what happened," Ellis told AFL.com.au after the Tigers' victory.
"You have your down weeks but I just didn't want to have another down week.
"I just wanted to get up and play my role for the team and help us get over the line.
"I had the job on Gibbs to run with him wherever he went, and I thought I did an OK job on him."
Ellis said he understood why he was criticised by Hardwick and knew he had to grow with the team.
"Dimma's just a tough bloke and it was the truth and he just wanted us to step up and for us to go places this year and the following years," he said.
"For that, me and Reece need to step up and improve our game."
Hardwick joked after the Carlton game that he was set to name 18 players in a bid to get the same response he received from Ellis and Conca next Saturday when the Tigers meet the Western Bulldogs at Etihad Stadium.
But he praised the young pair for playing the way they did off the back of the Suns' game.
"They were great. Brandon Ellis tagged one of the game's elite in Bryce Gibbs and keeping him to 12 touches was enormous for us," Hardwick said.
"We really put him to task and he delivered in spades. He kicked two crucial goals and he's going to be a very good player and to see he's got that in his game is outstanding.
"Reece was brave. He played on Murphy for the majority of the night and cramped severely in the last quarter and I'm not too sure how much game time he played in the last but I thought he was outstanding early too."
Ellis, who trained with the midfielders this pre-season, kicked two impressive goals against the Blues, one from the corner of the 50-metre arc and the boundary line.
He said he wouldn't mind adding more goals to his game after kicking just 14 last season.
"The first one I probably just pulled out of my backside. It was a bit of a fluke, but the second one when 'Newy' handballed it back to me, I just thought, stuff it, I'm going to have a shot," he said.
"Luckily it went in and the boys blocked it on the line for me so it was good."