Nowhere did you manage to quote Jesse Glover saying that he did not feel William Cheung was that good. Jesse felt not many in Wing Chun could really apply it practically, it is same for any art some train hard and work it under real pressure whilst others don't. William Cheung and Jesse Glover did Chi Sau and Cheung was all over him, Cheung said he thought what he did was crude and limited but still effective just not against the most skilled of Wing Chun people. Not sure if Jesse ever mentioned that in interviews but it was witnessed by numerous people, maybe like some of the Karate guys that sparred with Bruce Lee they have amnesia about it ever happening. The claims of others like James Demile that later people had weak trapping or Bruce began to leave out important things so they could never reach his level are not true and just for self publicity, besides people like Dan Inosanto, etc have trained with Jesse Glover and others from the earlier period and experienced what they do. Bear in mind also Dan Inosanto has trained with several renowned Wing Chun people :
Many in Wing Chun are firmly stuck in a Classical Mess as Bruce Lee would term it, same also for many Aikido people, many in old school or original Jeet Kune Do, Tae Kwon Do, etc. Though there are those in those arts who aren't and are very good at what they do, and have worked with other skilled people in other arts. Just ask many of those people in Aikido or original JKD which elite people trained in BJJ, Sambo, Greco Roman, etc they have been on the mat trained and sparred with, and tried their grappling defences against? Or ask how many elite level Filipino martial artists have they trained with to try out their stick or knife defence on? Or top MMA people they have trained and sparred with? Sitting in a neat protective shell training only with your own guys, pontificating how what you do would deal with a skilled grappler or someone trained in knife fighting is fantasy la la land and gives you a false sense of security. MMA is becoming more popular thus chances increase someone you fight at a local bar or in the street may have training in it, or just be skilled at grappling and BJJ, which is better sitting in that neat protective shell training only with your own guys none of whom are renowned in the martial arts community or seeking out high level MMA people to train with? The answer is obvious! You go to places like Philippines chances are a street attacker may have had some training in Filipino arts like Kali, not everyone there has trained in arts but certainly chance if you have an encounter they will be - better to stay in your neat protective shell with your classical mess or get out there and train with elite Filipino martial artists? Someone using old school Jeet Kune Do or traditional Wing Chun unarmed would be a gift to someone with even moderate skill at using a knife in Kali,if they trained with elite Filipino martial artists they would be aware of that! A Traditional Wing Chun person standing face on flat footed is a gift to any grappler trying to take them down, if they trained with elite grapplers they would realise that. Someone with even moderate skill who has not trained extensively in Kali will do attacks with stick or knife you are not prepared for, slashing at your wrists as you punch, slashing the inside of your thighs just standing or if you try kick which causes serious blood loss fast. You don't need to train for years in systems or devote your life to them but you better at least have been on the mat with high level MMA, BJJ, Sambo, Wrestlers etc as opposed to have stayed in a neat protective shell with just your own guys none of whom are renowned in the martial arts community.