He made his striking work, yes, but no one in their right mind would call him a technical striking genius. It worked because of other factors (like his speed and reflex advantage, the fear of grappling, etc), his stand up was good in spite of his striking skills, not because of them. And Mirko was shit in that fight.
It's not technical in terms of regular boxing/kickboxing, but it's a technique nonetheless, and he made it very effective, especially when he mixed it up with clinching and trips/takedowns. How could his stand up be good "instead" of his skills, that makes no sense?
Look, i love watching good technical boxers as much as anyone, but Fedors success in MMA was largely due to his unorthodox striking, which he used methodically. Later in his career (after Pride), when he decided to go full brawler and give up strength, he still managed to knock several heads off precisely because of his striking. Tim Sylvia got destroyed in seconds (looping hooks again), Arlovski (watch the slowmo-gifs, Fedor slipped most of the punches that people think Arlovski landed), Rogers, Henderson prior to the KO (the stoppage was legit btw).
Again, watch Khabib Nurmagomedov's fights, he's an undefeated lightweight who already beat the current UFC LW champ, he uses a similar approach. It doesn't look as pretty as say Conor or Robbie Lawler, but it works.
