Yes he is overrated. Its an obvious result after being the best NA midlaner, he gets so much praise.
The problem with bjergsen is his macro play. He's kinda like froggen. Mechanicly superior to his opponent ( at least in NA ) , most likely to have a CS advantage - in NA, great control lanewise. But he doesn't really set something up. The reason why people start noticing it atm is because league is evolving more and more from a game "get fed and win on ur lane" to "tacticly making better decisions and playing as a team" - And Tsm is just falling apart starting from the toplane all the way down. Right now TSM has to many holes, and they have not enough hands basicly to cover it. Cover one hole, the water pours thru the other basicly. Their macro is horrible.
Everyone has it's talent, there's hardly any palyer out there tahts completely all round good, faker, pawn and maybe 1 or 2 more have the capability to play in any meta, they're all round. Bjergsen and players like froggen are more centric to a certain playstyle.
Quite honestly, besides replacing dyrus ( obvious reasons ) i would most likely replace bjergsen aswell if theres on option for the more suited player. Doesn't even mean that player has to be mechanicly better.
Tbh tho, I find bjergsen mechanicly overrated aswell. He's good a good thought process of how lane matchups will turn out and what things can do, whta ranges things has, cooldowns etc. But the things he does, well koreans do it faster - On top of the better macro koreans has.
Bjergsen right now just doesnt have a single advantage against international midlanes which can provide pressure on the lane.
Thing is, right now if you're not so good at the macro play, you can still make up for it with huge mechanics. The only real talent from bjergsen is his lane dominance and having great mechanics - But thats the problem, he will alwyas get outshined mechanicly wise internatinoally , and theres no macro play to fall back on. Hai used to roam an insane amount and he'd accept losing his lane and just playd for the team.
Theres just nothing bjergsen excels at vs international midlaners.
and for the people saying tsm is overall overrated.. i've been saying that for ages, just look at how fast the macro is .. its insanely slow , sluggish, bad decisions, slow decisions.. and theres reasons for that, but thatd take an adittional 89359375hours of writing ..
The only tteam i'd have my faith in is CLG, they're looking pretty ok atm. I wouldn't take zionspartan to seriously tho on him thinking he can win world's with the current CLG. But they can suprise everyone with taking a fwe games in groups and move on to quarters etc.