CTE. I think Hrgovic has one of the few chins to survive Ruddock's uppercuts. Hrgovic has a good enough jab to control large sections of the fight and Ruddock is so wild and open whereby Hrgovic's solid right hand will do plenty of cumulative damage. Hrgovic is also defensively poor and he will absord horrific uppercuts from Ruddock, which he can survive due to his chin, but which will cause long term damage. Ultimately taller dude with the better jab wins. Hrgovic UD, 9-3 type fight.
I think you're overrating Hrgovic who I don't rate that highly TBH. A still good version of Tyson in their 2nd fight lost about 3 or 4 rounds to Ruddock so you're saying Hrgovic does better than Tyson in 1991 ? Hrgovic kept looking away vs Zhang when he got hit and he only won that fight because Zhang has no gas tank after 4 rounds. This would be a repeat of Zhang/Hrgovic except Ruddock wins more rounds because he can actually fight into the later rounds.