Floyd Mayweather Sr. refers to their upper-body positioning as "The Crab." I've done everything I could to trace the History of this. I learned from him that his trainer was Dale Williams. And it must have had some prominence in Michigan as a regional thing because many fighters from there use it. Though Sr. didn't use it as much as Jr. does. The predecessor of this style was invented by Tommy Ryan, and taught to Jim Jeffries who took it to the Heavyweight Title. If you very closely examine photos of Jeffries, things should jump out at you:
I'll give you a hint:
Though Ryan's version was referred to as "The Crouching Crab" because Jeffries kept his knees bent, and often moved almost sideways at the opponent. Baited with the left hand a lot (which Floyd Jr. does, and Sr. teaches).
Moore's style is totally different. One of the trainers at my Gym learned in San Diego under Archie alongside Billy. Archie himself referred to it as "the lock." From everything I've been able to dig up, it was taught to him by Hiawatha Gray, himself a bare knuckle fighter (as I mentioned in the Wing Chun thread on this main page). It makes a lot of sense particularly for bare knuckles or horse hair gloves, bang on the elbows and eventually your hands hurt or break.
It's been pointed out numerous times that the term "Philly Shell" was coined by a video game. However, there WERE a few Philly fighters who used a similar position as "The Crab" for their arms. Bennie Briscoe, and of course Goergie Benton as was referred to earlier in the thread. Also Joe Frazier, and a host of Philly Gym fighters (even loosely Rocky Balboa if you really pay attention to how Stallone moved, and he's been boxing recreationally for years), including Bernard Hopkins. Though I've never discovered how this ended up in Philly, it seems to have in common everyone Benton or Futch (who worked in both Philly AND Michigan) had any influence with.