Just a thought, when you bulk ferment dough for pizza, the gluten starts to develop during that period. When you ball the dough you are aligning the developed gluten and developing it a little more again. Therefore I would think with the bulk ferment you are balling with a higher gluten formation causing stiffer balls.
In my experience, if I try to re-ball a piece of dough that is based on using very little yeast (such as your recipe calls for), I usually end up with a dough ball that is overly elastic and hard to open. Sometimes that condition can persist even after a period of several hours, especially in the winter where my room temperature is on the cool side.
Speaking as a home bread baker, I will bulk rise my dough (I use a very long fermentation period), then divide it and ball it (or as we would say, make preforms). At this time, I'm looking to form loaves that will hold their shape without slumping as much as possible. So I often work the dough by stretching it when I form the preforms. This is pretty effective. Note that I'm using un-bromated flour.
The dough will develop gluten more the longer it is hydrated - I don't know that the yeast has much to do with it. Of course, if you put in a lot of yeast and get a lot of rise during this time, the dough will feel different, but within reason I think it's mainly time while hydrated that counts. Now, some of those new gluten links are weak, and when you stretch they either break and reform stronger, or align and get stronger. Later, as we know, the gluten relaxes and the dough finally gets more extensible, but that can take many hours.
So I'd say either to work the dough as little as possible when you ball it (the opposite of what I do for bread), or better, divide and ball it as early as possible in your processing cycle. Or both.