Stevenson, 21-0, joined Babcock on the "TMZ Sports" TV show (airs nightly on FS1) ahead of the Haney vs. Garcia fight on Saturday at the Barclays Center in Brooklyn ... and we asked Shakur for his thoughts.

"I kinda think [Ryan's] not focused. I don't think that he's really taking the fight serious," Stevenson said.

"It seems like he's more focused on selling the fight than actually working and making sure that he's coming 100% ready for the fight. I don't think it's an act."

Of course, Shakur's referring to Ryan's erratic prefight behavior ... Garcia has worried many fans and followers alike with his erratic behavior in the weeks leading up to the fight.

Despite those calls, the fight's not getting canceled ... so we asked Shakur to give Ryan a blueprint to victory.

"I think that he should go at Devin. I think that he shouldn't go in there waiting in boxing. He should go at him like he went at Tank and try to land his right hand."

SS continued ... "I think that Devin keeps his left hand down a lot, so try to land the right hand, not just the hook. I think Devin is prepared for the hook."

Can he do it is the question ... and Stevenson believes it's highly unlikely, especially 'cause he isn't all that impressed with Ry on his best day.

"I don't think that he's even on the elite level. I think that he's not really that good of a fighter."

We also asked Shakur how Devin wins.

"I think Devin just goes in there and does what he's been doing. I think he's just boxed his way to victory. He may even be able to catch Ryan, especially with Ryan being not as focused as he should have been."

Shakur says he won't be in the building for the fight, but he's eagerly waiting to watch from home ... and he's very hopeful he'll be able to reach an agreement with Haney that'll pit them against each other in the near future.

"I see myself fighting Devin. I think that's the fight."