Yes, Wemby also had some faults in some critical moments. But I wouldn't put it to him completely to be honest. Spurs had something missing as a team.
You have all seen how many times they got a really solid lead during the games. Game 4 was the craziest about it.

And Spurs threw away all of those potential wins just like that.
That’s why I hate how a lot of media and pundits are making a scapegoat out of D’Aaron Fox, they were willing to crucify him over 2 points play when collectively as a team they blew what was 29 points lead, If we’re to start micro analyzing their entire series collapse, there would have been a bigger portion of the blame on Wemby, and Stephon Castle more than it would have been on Fox, we all saw what happened in Game 1 and Game 2, and almost happened all over again in game 3… They failed as unit, and that’s the best way to go about it, they’re young and the talent is there, they should just use the loss as a learning curve.
I guess they will have to point to someone and blame him, and this time it was Fox, very unfortunate to him. But nevertheless, we have seen him making some good plays against the Thunder but it was overshadowed by this costly mistakes.
While it's hard to point the finger to Wemby as he is the franchise player of the Spurs. But if you look at it, if they can just hold on that lead and not committing those errors and not relying from the outside, the series might be very close.