What happens if you have poor endgame play...

Totally drawn endgame, turns into a win for me, cuz the guy had terrible endgame technique. We both missed the nb4/5 idea in the endgame.

There were even chances at the end like 67.Nb1 is a simple draw.

Yeah, seems to show a fundamental misunderstanding of what the endgame is about... and basically it's all about the pawns. Pieces are only useful to help win or promote pawns.

Which is why your comment about Nb4/Nb5 is strange. That's middlegame thinking. You think those square are nice because they're outposts or some silly thing like that, but those squares are pointless. Only squares where you can pressure pawns matter. Material isn't as important as queening.

For example 55...Kxa4 is a mistake.
55...Nf6 wins.
Nf6 is good because it touches a pawn.
Kxa4 is bad because white's g pawn is a passed pawn.
It's all about pawns.

Nb4/5 is actually engine recommended move in the knight only endgame, creates a one pawn advantage(I understood why once I saw the move).

I agree that he could have drawn at the end, his technique was just really bad.