It's been well known for years that the 1 inch punch is based on the mechanics of the Taiji punch with fajin ... Bruce also meditated and had some element of Qigong in his training so he was well aware of other styles and Taijiquan was one of them. The whole principle of remaining soft until the point of impact and snapping the punch like the tip of a whip is pure Taijiquan. His descriptions of keeping the fist relaxed and loose is exactly how we have our Taiji fist at all times ... this is what he took from Taijiquan and borrowed into JKD.
Regarding the Wong Jack Man fight ... do the research ... Bruce really lost that right and he knew it which is why he abandoned Wing Chun and totally developed a whole new style. Wong Jack Man held back and did not use any of his lethal kicks and only parried Bruce away cause he was going nuts ... Wong Jack Man was aware that it could get out of hand so he used restraint because Lee's temperament might have not handled the full brunt of Wong's attack ... he feared he would have to kill Lee so he was fighting defensively and doing enough to control the situation and keep a lid on it. I think it is very sad the way the Lee foundation have sold the story about that fight the way they have ... it's complete defamation of character and false, very sad.
Bruce changed his art because he knew he blew it.