Again it should be noted that Ip Man was going through a particularly rough patch mentally - IIRC on top of Frankie's (Mike Tyson) gangsters blockading his neighborhood, his martial arts school was foreclosed and his wife had developed ovarian cancer - and past his prime in this movie.
Nevermind that this isn't even the final fight of this film and apparently Ip Man 4 is in development. PAST HIS PRIME. TOO OLD FOR THIS SHIT.