I would blame management/top more, than sales. Sales can work only with products they were given. AFAIK Twitter was pretty aggressively hiring 2-3 years ago sales reps across the globe and they were stealing top employees from FB and co.
I would assume that it is the lack of products/top commitment that causes poor sales.
I agree again, I think there is a lot of blame to go around in Twitter, also another reason why I think they could have a healthy purge and move forward with some fresh vigor.
I would assume that it is the lack of products/top commitment that causes poor sales.