I agree with your assessment except that you incorrectly labeled McGregor as a “former MMA Champion”. He is the current UFC Lightweight Champion and former UFC Featherweight Champion. He did not lose the Featherweight Title. It was vacated/stripped when he moved up to the Lightweight division. However, he is the first and only UFC fighter to hold two belts simultaneously.
I see Mayweather vs. McGregor as speed vs. power. Mayweather is a counterpunch artist with speed of movement. He is very difficult to hit unless you trap him in a corner. McGregor is an aggressive striker with rare power and a great chin. If McGregor lands a strike, Mayweather will feel it and as you suggested, it will stun him. UFC fighters that have entered the cage with McGregor testify to his power. One of these fighters, Jose Aldo, who was 26–1 when he faced McGregor, had fought the best fighters in the UFC and never suffered a KO until McGregor knocked him out within the first 30 seconds of the fight. McGregor’s only loss in the UFC was a submission loss to Nate Diaz who weakened McGregor with vicious combinations but McGregor’s chin held up.
Mayweather hits hard but he lacks one-punch KO power. He hasn’t knocked out an opponent in over 9 1/2 years. Nevertheless, his fighter IQ and ability to evade punches with his speed of reaction and motion is legendary. He will also be faster with the larger gloves. I expect McGregor’s punches will be slower than those of Mayweather’s boxing opponents who are conditioned to fighting with the larger gloves — but McGregor’s success in the UFC has never relied on his speed. His striking and movement is very creative and unorthodox and, as you suggested, his punches will come from angles that Mayweather is not accustomed to defending.
MMA pundits have suggested that McGregor’s power will not be the same with boxing gloves. This is a myth that boxers, including Mayweather, have acknowledged is false. Mayweather and his father have commented that McGregor’s power is a concern and I expect they will employ a defensive strategy utilizing movement and counters with 2–3 punches in quick succession, similar to his fight with Pacquiao.
Other critics have suggested that McGregor will tire by Round 4 or 5 but I think conditioning will be a wash. Mayweather is 13 years older than McGregor and MMA is a more physically demanding sport than boxing due to the wrestling/grappling component. In McGregor’s second fight against Nate Diaz, a triathlete, he went all five rounds and his decision victory was credited in part to his superior conditioning.
My prediction is that Mayweather will successfully evade McGregor’s power strikes and coast to a decisive unanimous decision. However, like you, I agree that if McGregor connects with one solid left hook to Mayweather’s chin, Mayweather’s advantages in the boxing ring will be neutralized and McGregor may just shock the world.