Chewy Crust

I had made a batch of the Roman Crust from PR American Pie two weeks ago and used to balls immediately and froze the remaining balls for future use.  Last Friday I pulled two balls out and let thaw.  They sat on the couter under plastic wrap for around 4 hours.  I did a preshap of the dough on a floured surface with a rolling pin and then let rest for 5 minutes and then shaped to a 14 inch skin.  I topped them and baked the first one at 550 degrees on a stone and when that came out I placed the second one in. 

Both of the crusts came out chewy and tough.  The first ones I did came out great, did the freezing do something or is this simply a case of to much working the dough?