First of all about 3 year thing. He was clearly best until his injury in march/april 2016 so it's not even 2 years yet.
Nothing special LOL??? He was best player for 1,5 year that's maybe not the longest period of time but you have to consider and give him credit how much better he was compared to other top pro players at his prime, there was no competition, he was THE best player out of all best players in their eras. 2015-early 2016 olof's peek was just out of this world (Only one comparable would be kennys late 2014/early 2015 but short term cause of awp nerf).
He was consistently cracking bombsites open by himself with multi kills iconic examples cobble plato and main entrance on train which is literally called olof by him. He went first very often and still had best stats out of all players he didn't need to fucking bait and ecofrag hunt all the time as coldzera is doing or gtr who was playing more laid back role and stayed alive as last member most of a time. Olof was true and only one perfect player who had no weaknesses which is fact and proof of it is if you look at his stats in 2015 he was the only player above average in kills, assists, deaths, rifles, AWPing, pistols, clutches, opening kills per round, big performance in big games, and best at consistency as well throughout all year, he was good at literally everything in the game, no player did that in history of whole csgo and I think it's save to say no one will ever do (probably). Imo only thing that stopped him was wrist injury from which he sadly never fully recovered.