"Bro, [Jake's] a little boy, and I'm gonna treat him like one. That's what Woodley didn't do. Woodley gave him too much respect, and he sat back with his hands down and he got caught," 31-year-old Rahman Jr. bluntly said when we asked where Tyron went wrong when fighting 25-year-old Paul.

And, 6'3" Rahman Jr. -- who has previously fought north of 260 pounds -- believes he has another advantage ... size!

"All of Jake's opponents have been smaller than him. All of them have been much smaller. This is the first time he's going to be in there with someone that's walking him down and much bigger than him."

Paul -- who's 6'1" and was 191 pounds when he fought Woodley (T-Wood weight 189 for 2021 rematch) -- has faced fighters who all stand under 6 feet (Gib, 5'9". Robinson, 5'8". Askren, 5'11". Woodley, 5'9").

Rahman Jr., 12-1, just fought April 29 ... where he suffered his first loss, via TKO. But, that didn't stop the son of the former 2x heavyweight champ from accepting the Paul fight when Tommy Fury dropped out ... even though Hasim claims Jake made him accept strict rules meant to diminish the heavyweight boxer in the ring.

Hasim says although the fight will be contested at 200 pounds ... he'll only be permitted to rehydrate to 210 pounds just hours before the bell rings. A guy Rahman Jr.'s size could typically gain 15, 20 or more pounds in between making weight and the fight.

"If you really wanted to make a statement you would've came up to heavyweight and fought me. But you didn't. You wanted to bring me down, and stack the deck against me, so you could actually have a fighting chance. He knows he has no chance against me had it been at my weight class," Hasim says.

We also talked to Rahman Jr. about Logan Paul advising his brother to not take the fight, and much more.