Peak Jones for me. Beterbiev is a tank but Roy at his best was other worldly. Clear UD with a possible knockdown as well imo. That movement, lightning hand speed and power is a problem for anyone Artur included.
Roy would present the same issues Bivol did but add in stopping power to the maximum. Beterbiev would lose UD or late TKO imo. I don't think Artur catches up to him as he was not really able to catch up to Bivol tonight except for after Bivol had tired himself out due to activity. I think Artur struggled with that movement, range and activity early on from Dmitry--RJJ would expand that to the umpteenth degree and add devastating power and angles to it. Roy wins this.
Maybe Roy would be too fast & classy for Beter, but Beter has absolutely freakish 2-fisted power, the kind of power that sends opponents reeling backward just from touching them w/ a jab - I don't think Roy has ever shared a ring w/ that kind of power. It only took 1 little left hand from DelValle to slip thru Roy's guard & turn his legs to jelly - Roy would be under the same kind of threat all night long from Beter.
By that same notion though Beterbiev was put down heavily and was on wobbly legs against Callum Johnson who is not world class. Yarde also gave Beterbiev a very good argument and buzzed him a few times aswell. So whilst I agree RJJ never fought many big punchers like Beterbiev by that same notion Beterbiev hasn't really fought alot of upper echelon fighters either. Beterbiev's power would be a danger to RJJ but RJJ's power would also be a danger to Beterbiev. RJJ has some very impressive displays of power at Light Heavyweight. RJJ was the only fighter to stop the very durable Clinton Woods, RJJ stopped Virgil Hill with a single body shot, and rag dolled Montel Griffin all over the ring in 1 round in a frightening display.
Prime Roy stops him tbh. I don't think Bet's defence is good enough to negate the hand speed and foot speed advantages that Roy would enjoy over him and I think one of those hookercuts or straight rights starts the end of it for him. Bivol caught him with combos that Roy would reel off for fun like the auction man. If Bet cracks him solidly, there's every chance that Roy gets caught, dropped and doesn't recover but I think Bets would have to lose 1 or 2 fights to catch Roy's timing and speed difference.