You have a hypothesis, that’s it. You suspect distance will be lost, but you have no data to substantiate it. You can’t tell me how much distance is lost.
Reasonably speaking, the JV swing starts in a pre-loaded position, with the hands dropping which promotes optimal shaft flex and lag. Pro golfers with a traditional swing can hit the ball well enough to have optimal lag and shaft flex combined with using some extra muscles to get more distance than the JV swing can provide.
Totally reasonable to conclude that. What we don’t know is if those extra muscles give an extra 2% or 20%.
Then factor in the consistency of a simple vs complex swing. Pros aren’t terribly consistent (the traditional swing is hard!) and arguably many pros would benefit from a more repeatable swing.
I’ll agree on one thing, if JV wants to promote his swing beyond the weekend warrior he’ll need data. I however am convinced through my own experiments that if I lost any distance I can’t measure it on the course, and suspect it would be the same for pros.
It’s not the best data, but it’s what we have. I think the distances are fairly accurate. 240 is a long drive for anyone without a single digit or below handicap. I wouldn’t read too much into each year’s data.
I think you can test the power of the swing yourself. Swing using JV's method without hitting a ball (to make it easier) recording your club head speed with a swing speed radar and see how it compares with other swing methods.