My class of 20, two couldn't cut the mustard in the sim. One went to Gojet, other last I heard pdt.
Mesa does not want you to fail, they really don't. I hear horror stories at PSA. If you went to ALL ATPS and did well there in the fast pace environment, Mesa will be a walk in the park. I keep hearing captains in the crew room talking about newhires who can't fly worth a damn. Captains wondering how these guys made it past ioe, let alone the sim! So I doubt many are failing.
My own point of view is that these bad apples need mentoring in a stress free environment and be groomed into excellent pilots. Difference between someone who is considered good vs bad is how much time they required, in this environment. Regionals like Mesa cannot afford to let pilots go that can be made into good pilots.