Didn't see this before, but how is there a certain truth to his argument? If one person proved him wrong, there is 0 truth to his argument. He's never trained anyone to jump high because that isn't their goal. Ok. He shouldn't be making the claims he did then.
When we are talking in absolute terms you are right, he would be proven wrong by anyone who increased their SVJ by more than X %, something he claimed to be impossible. But if people would see beyond that number and grasp the actual thought behind it, there would not be as much controversy about that topic. The thought being that in reality most people fail to increase their SVJs by more than a small margin. When Kelly, who hardly anyone here would not see as an expert in the matter, comes here and says that the typical improvement he tells his clients about is 30% in a reasonable time frame, what does that tell you? It tells ME that certain people who have an interest in increasing their jump and are motivated enough about it to do some research and actually contact Kelly Bagget to ask for advice or even pay for his services, are untypical to improve their SVJs by much more than 30%, despite the fact that they are a preselected group of athletes to begin with and are provided with solid training information as well.
Can we conclude from that, that X% is the maximum of possible improvement? Of course not and even one black swan is enough to prove that statement bullshit. But what can be said is that X% might be typical, what most of the time happens in a certain population with a specific training goal. In Rip's population >X% happens less often than maybe in Lance's population and that probably has a number of reasons, one of which you have mentioned yourself. But the general idea behind giving such a number to a trainee that is starting out is to give him a realistic expectation to work with and not tell him that he is likely to increase his SVJ by 50% because one person on adarq.org has done so.
The biggest issue with those statements of Rip were phrases like "impossible", "every", etc. I can understand that people have a problem with that, especially when it concerns themselves. The discussion would be more fruitful however if people would stop pointing the finger at Rip for making a claim that was doomed to be proven wrong by
someone from the beginning and instead concentrate on what was, I believe, actually meant by it. Namely what is typical, what generally happens etc.
Now, questions like "In which populations is that the case?", "What are predictors for success above the average?", "What might be the effect of treating the SVJ as diagnostic tool vs. as athletic skill to be practiced?" etc. are actually meaningful topics that could have been debated if it wasn't for the stubbornness on both sides to prove the other side wrong.
I sincerely hope that there will be a meaningful debate about the half-squat and its value as SPP exercise, about possible and typical SVJ improvements etc. once we have made our case study.
