I am still trying to figure out this "shift punching" thing.
On the related subjects:
Penn vs Diaz
I agree with RogueVampire RE Diaz. Diaz vs Penn looked good for Penn on paper, but I thought BJ could find a way to lose and he did. Diaz comes with a high work rate, good chin, and seemingly great cardio. Those things play into BJ's weaknesses quite well.
The reach advantage makes BJ landing his jab less of a sure thing. BJ had/has "great" boxing by MMA standards. He has head movement, timing, power, and uses his jab to set up other punches (as opposed to simply jabbing all night a la GSP). Thing is; he needs his jab to land in order to do it. He also likes to stand in front of his man "in the pocket". This is harder to do against someone taller, and much harder to get things going when you cannot keep up with the other guy's work rate.
We also have 2 Penn vs Edger fights to watch that tell us what BJ does when he cannot get his jab established.
Bareknuckle Boxing vs MMA boxing vs Boxing
Rules/competition drive the real style differences here.
In modern, gloved, western boxing there is very little to be gained by concentrating on clinching. Cameras/re play, enforcement, and general public responses have made much of the "fouling" or "rough fighting" of the early gloved era a poor gambit. The incidental/accidental head butts, elbows, and clinching that was standard into the 50's is a rarity now.
So, if you were developing a young fighter would you spend time training it or just working the jab? Modern reporting shuns the "dirty fighter" and the reffing is done to limit its benefits. Amateur boxing still rewards quantity of blows vs. effect of blows and that colors the style as well (this may be changing, there was a thread about it).
Bareknuckle/London Prize Ring rules were sort of a boxing/Greco hybrid as far as technique goes. Keep in mind there were no judges, so any strategy that costs you energy and DOES NOT move your opponent further to being unable to continue is wasted. There was no round limit and your hands were unprotected. This means that not wasting energy or hurting yourself in offense was a much bigger consideration. So, a more plodding slow paced style starts to make a lot of sense.
Add the fact that the surface could have been hard wood, dirt, stone, or a grass field and much of the footwork that makes modern boxing what it is becomes impossible. The final note; a knockout count was 30 seconds with an additional standing eight to come to scratch as opposed to 10 sec and there were no set max of rounds. A round ended when either man touched the ground with any part of their body other than their feet. So how would you fight under these rules?
In MMA boxing is just one facet of the game. Hell, it may not even be a "facet" unless we consider all punching to be "boxing" proper. In MMA everyone needs to contend with kicks, clinching, takedowns, knees, elbows, etc. at least for defense. Whatever a fighter wants to accomplish offensively also plays into how they need to stand and move. In another thread JonnyTMT posted a couple fight videos of Thai boxers doing what they do. If they were competing under amateur boxing rules than their stances and movement would be suicide.
Under Thai rules there are VERY good reasons for doing what they do. Are they susceptible to single and double leg takedowns? Fuck, maybe...probably yes, after all there must be a reason wrestlers and Judo guys stand the way they do. Of course wrestlers are not dealing with getting hit. The varied "tool box" of MMA really opens up style options.
Final note on this topic; let us consider style vs Style. There is clumsiness with these terms. Boxing is a style. In boxing we have all read/heard "styles make fights". Pac and Mayweather are both boxers. In MMA terms we would write that as their "style". They also have very different "styles".
Nick Diaz and his style (or is it Style) of boxing
Yes it looks different than most boxing. It also looks different than most MMA stand up. If it was really the be all end all for dealing with takedowns, than Nate Diaz( who uses a style quite like his brother)would not have had the showing he did against Guida.