Along with what Tom said, the timing was horrible; Miami was under performing, FSU and Clemson were still on the upward climb, etc. The ACC probably would have gotten more money had they at least negotiated somewhat with Fox for part of the rights. Such is life. By the time the deal comes up again, much of the delivery we knew 5-10 years ago will have changed.
What no one is talking about right now is that the SEC is in their deal for about two decades more. Imagine how far they could be behind by then.