Usyk handed Joshua consecutive defeats, the second of which forced AJ into a bizarre post-fight rant.
But the British superstar returned with a victory in April, beating Jermaine Franklin over 12 rounds.
The performance drew criticism with the likes of Carl Froch and Johnny Nelson joining fans in questioning Joshua’s mindset.
But ex-opponent Usyk has leaped to AJ’s defence, telling Boxing King Media: “I think he just needs a little more time to recover.
“He’s a great fighter and a great personality. And who are those people who judge him? Who are the judges?
“Have they ever entered the ring? Have they ever trained and felt that pain? They have no right to say so.
“If you want to talk about a fighter, you have to at least once in your life get into the ring and have a sparring session.
“At least for one round, for three minutes. Then you will have the right.”
Usyk, 36, is set to face WBA mandatory challenger Daniel Dubois, 25, next after his promoters won the purse bids for an August 26 bout.
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Meanwhile Joshua, 33, is in talks to return against Dillian Whyte, 35, on August 12 in a rematch after his 2015 stoppage win.
It comes with AJ also in line for a December blockbuster in the Middle East against Deontay Wilder, 37.
Although Hearn has revealed no offer from backers in the Saudi Arabia has come through, with their current attention on Whyte.
