Based on his original post he is trying to argue that Fedor's punch is all technique and that straight punches aren't always better than wide looping punches. Then he goes on to theorize--incorrectly--that the reason is because of the glove size. Then he goes on to imply that it helps to protect your chin and setup for the takedown.
Note the bold here on his first post:
So what I wrote was actually in line with his idea that straights aren't always the answer--because there are no absolutes. I don't think I said anything about a curved punch being compact or loose. Nor did I comment on the idea that it protects your chin or sets up a takedown better than any other punch.
That said, I believe that keeping your chin down and your other hand up is what protects your chin...and what sets up a good takedown is timing, distance, and control. The idea that throwing a hand out in the hopes of rushing in to wrap up the opponent isn't the best idea when you have someone who is a fast and compact counter puncher. The long and short of it is his argument for the casting punch is weak and without merit.
You have to remember that boxing evolved from bare-knuckle boxing, where standing grappling was allowed and fists had no gloves. So if the casting style punch was all that effective it would have evolved with the art of boxing. Instead, the popular punches were the straight punches with the palm up because doing anything different often ended with broken knuckles. FWIW...the casting punch can just as easily be replaced with any overhand right/left, leaving the puncher with less likelihood of ruining his shoulder and retaining the ability to use the same punching angle.
I agree. Looping punches can be likened to the shogun or hail mary pass as a last ditch effort to win the game in american football. If the pass connects, there are big payoffs--but more often than not it doesn't connect and still ends with that team losing the game. Why does it work in MMA? Because the striking game isn't as developed as it is in other striking arts.