They need to do more than get rid of the higher up executives. If they aren't that good, then everyone from middle management up needs to be cleared out. What they do instead is regularly clear out others and it results in nothing but a weaker environment and more fear-based maneuvering (which is probably what's desired given how weak Twitter's management is).

Twitter gets fairly good ratings on Glassdoor overall, but settles on a 3.2/5 for senior management (ie, even Google's 3.9/5 rating is reflective of poorly regarded senior management). In order to think of management as good (according to Glassdoor), they need a 4.0/5. If they get a 4.2/5 or higher, then they can be considered elite or special.

That is, they need to get rid of their crap middle management that's likely getting in the way of everything and driving it all (slowly) into the ground, then use the space that creates to get people in who know what they are doing and that are about progressing forward.