Vercingetorix wasn't the only leader in the city of Alesia during the siege. All decisions (attacks, retreats, army and food managements and so on... ) had to be decided with a consensus with the other Gaulish leaders... Which add complexity to this situation.

It was a terrible mess between them and probably some calls could have given advantages to the Gaulish and maybe a different outcome to the siege.

You have to get in mind that Vercingetorix and Caesar were long time friends before the siege so they knew each other's strengths and weaknesses. So, Vercingetorix knew what he was doing but sometimes, not listened.

I am blaming the Gaulish leaders for bad managements and Vercingetorix took the fall.