The main thing that would give Byrd problems, would be Corbett's use of angles. He would not stay in one place for Byrd to set up the jab, instead circling and countering. Technically orthodox fighters often struggle against fighters who do this, and also against fighters who are unorthodox and unpredictable in the way they throw punches. Corbett would also force Byrd to come after him, which is not Byrd's usual game, so we don't know how he would cope with that. When I say that Corbett would give Byrd problems, I am saying that regardless of the outcome of the fight, Byrd would struggle a lot.
You have absolutely no way of measuring that. So Corbett would have some major problems in adjusting, then. Except, of course, the small issue that he boiled himself down and Corbett did not. If you look at the pictures of Byrd at 175 he is ripped AF and Corbett looks like an accountant that stepped out for his lunch break. And I reiterate: Byrd had a 47% KO rate against much larger opponents than Corbett fought, who had a 25% KO rate against guys that in some cases might make MW today.
Except for the small fact that Corbett used exactly one good slip and circle in the footage and the rest of it looks mostly like slap fighting. And I think Corbett would get destroyed because Byrd is stronger*, faster and more busy than anybody he ever fought. I think Byrd's punching technique generates more power than Corbett's slap-fighting. I think Byrd's own movement is better than Corbett's and that Corbett would never have met a fighter that could flurry and body sway like Byrd. I think Byrd's more than twice the amount of fights would provide him with a wealth of experience that Corbett did not have. In short, I disagree with you. *Edit: with Jeffries and Sullivan excepted.
No but I don't think that anybody but the most blinkered modernist, would try to argue that Byrd hit harder then the hardest punching 200lb fighters of another era. Potentially yest, though he was more accustomed to fighting smaller men than himself. A guy who can make 175 lbs at the age of 37, without actually cutting his leg off, is not going to be an exceptionally large heavyweight in any era. KO% is almost meaningless as a measure of power. Most of Byrd's stoppage wins come against non elite opposition, so I don't think that it is a particularly strong argument in this case.
By "slap fighting" you presumably mean feinting. Has it ever occurred to you that Byrd might have been busier because his fights were much shorter? Hard to chalk it up as an advantage in that context. Which fight would you name as showing that Byrd's movement was better?
A feint is only worth anything if the actual punch it threatens is of consequence. Oh, I'm very comfortable in predicting that Byrd would dispose of Corbett before 12 rounds were up. I already posted a highlights package. Take your pick.
What jab?! Punching wasn't invented until April 27, 1956, in honor of Marciano's retirement. And even that wasn't very useful until Ali invented the human fist in 1965. It is known.
I don't see why that matters. If his record was otherwise the same but he also knocked out 40 total bums, I don't think that'd make him any better. His record is against many of the best of the era. Choynski, Kilraine, Jackson, Sullivan, Sharkey, Fitzsimmons, Jeffries x2, McCoy. It's like saying Loma is rubbish because he's only 11-1. Matteo Modugno is 20-0, but he obviously shouldn't be ranked close to as high as Loma or Corbett. Personally I think he looks very good on film, unorthadox, but gets away with it because of talent and speed, and there's a fair chance that wasn't him at his peak.