All boxing games are typically fundamentally flawed. First, the KO and KD system is often backwards. KOs and KD happen more more readily early with the chances of either going down the later you get into the fight. The worst time to get hit with an opponent's best punch is round 1. They are fresh and their focus and punching power is augmented with the intial rush of adrenaline that most fighter experience at the beginning of a fight. Thereby a fighter is more readily take advantage of a mistake and hit with much more power than would be possible later in the match when the adrenaline's effects has worn off and fatigue has set in.
Second, until FN implements a robust feint system, the counter system will always be broken. Feinting is an important part of boxing even though its a skill not readily apparent when watching it. In reality if you're faced by an overly aggressive boxer that just wants to counter, you just feint him into throwing counters and counter punching yourself. Your feints will discourage him from trying to counter everytime you try to punch and you'll have better success hitting him with lead punches.
Drastically, up the chances of flash KOs especially early in the fight and implement a good feint system and FN will mirror real boxing more closely.