I don't think that is a surprise, considering the lack of support in some circles for the timing offered, which was three days mid-December.
Another reason, and a big one...
Sankey and Delany want to revamp the whole recruiting calendar if they're going to do an early signing day. That's why this one didn't pass. — Andy Staples (@Andy_Staples) June 17, 2015
I bet the devil is in the details here. There is a consensus for having an early signing period. There is no consensus among the P5 schools about what that should look like.