Hi,
I think that trying to figure that out is a bit of a loose end, and your ability to conceive it is going to get more difficult and weird.
Suffice it to say that there are other methods of learning and studying music ... and that not everything is western philosophy related and can only play rock music chords that make it all a progressive band.
There is a lovely example in one of those Live BS events ... and it is with Bruce Springsteen. One of the people in there is the violinist Shankar (lots of ECM stuff too!) and he is playing something and Bruce finally stops and asks ... what key are you in man? ... to which Shankar simply says ... You, don't worry my friend, you just play and I join in with you!
What does that tell you?
One man can only tune in to you via notes and chords. The other? ... yeah ... a lot more ... and you have a good question about where, or how it is gotten or found.
It is believed and thought (very Gurdjieff this one is) that when your concentration is better, you can do more. If that is so, when it comes to music, you're either going to play more notes, or your feeling variations are going to bowl people over!
Since John uses "mahavishnu" and that means? ... vishnu is the preserver god of the Hindu sacred tirad of Gods. The term "maha" is not exactly defined or a derivative of a word that I could find. But this is my take ... "maha" is "the servant of", or "the disciple of", or "the partner of" ... and it probably has a similar placement as "maharishi yogi" for example. So we can suggest that he is a follower of a Hindu religion.
Now ... comes the hard part. I think that "maha" is a term described to folks/people that master something and are capable of showing it, in a way that inspires others. And it would also suggest that John's guru, or person that inspired him probably gave him that name for his ability!
Now the harder part.
If the concentration is better, it could be suggested that he can remember more notes and chords. However, this would not necessarily translate to his ability to play faster and stay in control of the notes he is playing ... and on top of it, make use of effects to augment his playing ... which he did massively!
I believe that he simply had the inate ability to play things fast. And that with the spiritual learning and concentration he learned the required levels to be able to play what he did and does, and not make errors, when the time comes, something that it makes you wonder ... how anyone can do that.
The collaborations is another interesting story. When you are next to a musician, even as a kid that is really good, you want to do better and better by him/her and in the process you sometimes don't realize that ... you got better! I like the recent bit that Stanley Clarke wrote and is playing on his new album ... something about waiting for Vishnu to ... but he will never deny the chemistry and the work that was done at the time, and that they made some amazing music ... and John was a big part of it ... as were all the others.
Sometimes it takes a visionary, or someone that sees something that no one else does. Vishnu may not have come yet, but Stanley ... you missed the boat ... the music has already come! Vishnu is already here through your hands!
How about that?