I may be in the minority, but I don't regard the AD role at GMU as a crucial linchpin. In the 30+ years since I graduated the ADs have come and gone and none have really had much of an impact as far as I can tell (O'Connor hiring Larranaga being a notable exception). In my experience the only time I seem to pay any attention to the AD is when there is a screw up (and there have been several notable ones over the years).
The one person that can and has made a difference when it comes to athletics (the basketball team, in articular) is the President, and the last guy that really moved the needle on this front was George Johnson (got the Pat Center built and was the 1st person in the school's history to recognize the importance of, and invest in, mens hoops). Maybe Merten gets a little credit, but I don't recall any major investments in the program following our FF run.
I thought Washington had a similar vision to Johnson when he made the big splash with the English hiring, but maybe that's not the case.
One of two things happened here:
1) Washington and Co. dropped the ball and mismanaged this situation. i.e., should have proactively extended English, given more money to assistants, made other investments in the program, etc.
or,
2) English was ready to go, Providence gave him an out, and nothing was going to bring him back.
I tend to fault Dr. Washington and the admin but it's possible English already had his bags packed and has been looking to exit at the first good opportunity.