I thought that my NCOER's would hurt my MEB/PEB because I wanted an unfit finding. My evals were all very good but my commander, 1SG and doctor recommended discharge so I ended up with the unfit finding I was looking for.
It is worth pointing out that your evaluations are only one "piece of the puzzle." They can hurt, help, or not impact things much. If they support what the rest of the evidence indicates, then it can push a result in that direction. However, if they are conflicting or do not address issues, they may be ignored. It is hard to make a generalization about them.