In our organization it would be beneficial to require multiple people to ALL pre-approve the change. Sometimes an administrator will not have the full picture and allowing them to unilaterally move the ECO to open results in work being done that is eventually rejected in the review stage, not because the work was bad but because the ECO was flawed. Having multiple sets of eyes "pre-approve" the work would be beneficial.
One possible solution would be to have a check box (similar to the unanimous approval check box that already exists) that requires unanimous approval from all approvers and one administrator to move the ECO from "open" to "work".
It could also have one more option in which it is required that at least one approver and one administrator is required to move the ECO from "open" to "work". If you were to add this option obviously it would need to be configured more like a set of radio buttons where only one of the options could be selected.