NEW YORK – Once Bob Arum learned Andy Ruiz Jr. weighed in at 283½ pounds, his former promoter determined there was no reason to even watch Ruiz’s rematch against Anthony Joshua.

Arum decided then that Joshua would definitively defeat an out-of-shape Ruiz in their 12-round fight Saturday night in Diriyah, Saudi Arabia. The 6-feet-6 Joshua (23-1, 21 KOs), who came in 10-plus pounds lighter than he did for their first fight, out-boxed a poorly prepared Ruiz (33-2, 22 KOs) and won a unanimous decision to take back his IBF, IBO, WBA and WBO heavyweight titles at Diriyah Arena.

Ruiz officially weighed 15½ pounds more for their immediate rematch than he did the day before he upset Joshua by seventh-round technical knockout June 1 at Madison Square Garden. Heavier and slower, Ruiz had difficulty dealing with Joshua’s movement and landed only occasional punches against his taller, rangier opponent.

“I knew,” Arum said before a press conference Wednesday at Madison Square Garden for the Terence Crawford-Egidijus Kavaliauskas card. “George Foreman knew. Anybody that followed boxing knew that it wasn’t even worth it to watch that fight. Wasn’t worth it, because [Ruiz] had no chance. It was Buster Douglas redux – no question about it.”

Douglas was a 42-1 underdog when he knocked out Mike Tyson in February 1990 to pull off what’s remembered as the biggest upset in boxing history.

A Douglas-Tyson rematch never took place. Instead, Evander Holyfield knocked out an ill-prepared Douglas in the third round of Douglas’ first title defense eight months after he upset Tyson.

Joshua was more than a 20-1 favorite over Ruiz during the week leading up to their fight six months ago. Ruiz admitted after losing their rematch that he celebrated his life-changing victory too much and lacked discipline during training camp.

“It happens all the time,” Arum said. “The difference is if it’s not in the heavyweight division, the guy still has to make weight. So, there’s certain discipline that he has to go through. In the heavyweight division, you can come in any weight you want. And so, there’s almost an excuse for a lack of discipline. I’ve seen this a lot. I’ve seen it a lot, you know, with heavyweights, mostly with heavyweights. I mean, [Roberto] Duran could eat a lot and so forth. But Duran never failed to make weight.”

Weight woes have plagued the 30-year-old Ruiz since he came in at 297½ pounds for his pro debut 10 years ago.

“It’s not like we didn’t have experience in that way,” Arum said of his time promoting Ruiz. “This happened to us throughout his career. He’d give great performances when his weight was down, and then he’d come in 40 pounds heavier. He has no discipline. He never had discipline. Look through his career when he was fighting with us, the different weights and everything. This was typical, typical Andy Ruiz.”

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.