Oh no, I'm not implying they're unskilled, though I would heavily disagree the skill level required is "insane". People have been pretending he's like 3x harder than he is to justify his ridiculously overloaded kit since his release. Saying it doesn't make it so.
He's still a ridiculously overpowered champion (he's been in the top 3 junglers, usually the top jungler, since his release years ago for a reason), but that's not to say people aren't skilled users of him. I just think the overwhelming majority of the work is done by the champ itself. He's got a disgusting amount of mobility and a disgusting amount of answers to any situation. A good Lee Sin never has to fight a battle he doesn't want to, and that's just plain bad.
Again, the player's reaction speeds and quick thinking are definitely commendable, the fact that this "big play" is even possible is not, and is evidence of a distinct balance problem with Lee Sin. The player didn't bait around the Irelia, or manipulate cooldowns or damage in a meaningful way, he just did basic Lee Sin stuff as fast as he could and got way more results than he should have from it.
A trend amongst the Lee Sin community: literally anything they do utilizing even the most basic part of his way overloaded, over-mobile kit is "outplaying" someone. You don't see Caitlyn's saying "outplayed" for landing their Qs, or Nasus saying "outplayed" for farming his Q. It's a unique trait of Lee Sin mains to think just using his skills is indicative of major skill, and, while it's annoying, it's not the fault of the players. It's the fault of a champion design with way, WAY more tools than almost any other champion, and flashy, fight-changing ones at that. Thats what I'm getting at.
I in no way meant to imply the player lacked skill.