I’m with ks629 on this one. EV is only one part of the project and represents only one aspect of it. Any EV estimate whether under budget or over budget will need to be accompanied by something to back it up and see where the estimates are coming from. By understanding where the origins of the estimate are coming from then you as a project manager will be able to make better decisions on how the project should proceed. However, again all accounts of the project should be taken into account and not just one aspect like EV.