The mazzei injector is used to mix air and water under pressure together which it does so very well. A beckett the same principle but uses a different style of injector as seen in the link I provided above and does take some more maintenance to keep clean. A mazzei injector is much more basic then a beckett. The under pressure part for both a mazzei and a beckett I believe makes them better at aeration then a standard needle wheel skimmer that will just chop the air up as it is passed into the water flow with no pressure. The needle wheel skimmer will pull more air but IME does not do as good a job at injecting that air into the water.
My trial with the Mag 18 and the mazzei 684 and 784 proved that to me. I was pulling out just as much and more skimmate with the Mag 18 that only pulled about 12-14 scfh of air compared to my Aquamaxx EM300 that was pulling in ~38scfh.
https://www.reef2reef.com/threads/mtc-mvx-skimmer-review.252436/page-4
Also, with the Mag 18 at 12-14scfh I was I maintaining my pH just as effectively as the Aquamaxx EM300 at that 38scfh. Pretty astounding to me and was a shock when I started this whole adventure with the MVX skimmer. Now that I'm pulling well over 20scfh with my mazzei I barely have to pull any air through my CO2 scrubber and I'm producing 6x as much skimmate then I was at 38scfh with the Aquamaxx.
So, air draw alone does not paint the whole picture I don't think. Dwell time is very important and how it's injected along with a balance of neck size. I really don't believe that the shape of the body at all effects anything or any kind of bubble plate or anything else that added to the inside of a skimmer. Just air, properly mixing, small enough bubbles, enough time in water, a clear neck to work it's way up, and stuff to attach to a bubble is all that's needed. Get those things right and you have one heck of a skimmer.