Boxing fans know the 6'7" power puncher has had a rough go of it lately, taking an L against Joseph Parker by unanimous decision in December. The defeat came as a shock to many fans who believed the Bronze Bomber would steamroll the fellow heavyweight.

Post-fight opinions on 38-year-old Wilder have now changed, with many believing Deontay's best days are long behind him, despite his great 43-3 record.

But, don't count the legendary RJJ among those people ... 'cause Jones Jr. still feels Deontay's an elite fighter -- and he even used a few UFC stars like Conor McGregor and Georges St-Pierre to make his point.

"Come on man, UFC guys have 5, 6, 8, 9 losses and they still put on good fights," Roy said, adding, "but why boxers can't do that? Just because he lost, that don't mean it's over."

The 55-year-old former world champ also believes Parker (34-3, 23 KOs) was just good enough to go toe-to-toe with Wilder and beat him ... assuming Deontay wasn't as focused as he would be against an opponent like Tyson Fury or another huge star.

"You gotta be in overkill or he gon' beat you," Jones Jr. said. "That's kinda what I feel like what happened with him."

"I don't think Wilder's washed at all. Wilder gotta have a fight that intrigues him."

FYI, before Parker, Deontay beat Robert Helenius by first-round knockout ... rebounding from two losses to The Gypsy King. Those are the only losses of his great career (43-3-1, 42 KOs)

Until then, Jones Jr. has his own fighters to watch ... undefeated super middleweight Andrew Murphy, who will fight Devontae McDonald in a 10-round bout on January 25 at Legends Casino in Toppenish, Washington. Indian boxer Mandeep Jangra will also face Gerardo Esquivel.

In fact, RJJ says Jangra reminds Roy of himself  ... which makes a lot of sense when you consider his nickname, "Indian Roy Jones."

"He does try to fight a lot like the way that I fought," Jones Jr. said. "My philosophy."