In real life Daniel would had lost all his fights
In part 1: Daniel vs. Johnny and the Cobra Kais
Daniel got only approx. 2 months of training.
Johnny and the Cobra Kais had at least some of years of training.
In part 2: Daniel vs. Chozen
Daniel now with 8 months worth of training.
Chozen was a master with training from since childhood and with the same style Daniel used. (Miyagi's father trained both Miyagi and Sato. Sato trained Chozen)
In part 3: Daniel vs Mike Barnes
Daniel now with a year of training.
Mike with black belt and many years of training.
YES, I know it's movies and in movies like this the good guys always win, despite impossible odds. (It would't be much fun if the good guys always lost, right?)
But if this was in real life, Johhny, the Cobra Kais. and Mike would had kicked Daniels a$$. Chozen would had killed him within 10 seconds.