Christopher,
I agree with what Bill has said, but I am also wondering whether temperature was a factor in your sub-par results. You didn't indicate whether you temperature adjusted the water or how much preferment you used, but if it has turned cooler where you live, as it has recently done with a vengeance here in Texas, your room temperature may have turned cooler also. That will affect the degree and rate of fermentation. Also, your preferment may not be warm enough to really perk up. What I personally do under these circumstances is to use warmer water, more preferment, or both, or I use a longer fermentation time, or I use a simple proofing box (you can also use a slightly warm oven) to get the temperature of the preferment and dough up several degrees. I don't use a stretch and fold technique but I don't see offhand why that should make a difference.
I assume that you have not changed anything else, such as the oven temperature or bake time. I mention this because a dough will sometimes have an underbaked or raw center if the pizza isn't baked long enough or if the oven temperature is too high and the bottom of the pizza is done before the top. The rawness can also happen, of course, if you use too many toppings or too many raw toppings, especially raw vegetables. You mentioned that you used a pan for baking the pizza. That can also be a factor, especially if is a shiny, unseasoned pan (e.g., of bright aluminum). Whether or not the pan was implicated in your results, I would suggest that you use a pizza screen instead if that is an option since the screen will give you a better oven spring than a solid pan. In my experience, a cold pan with an unbaked dough on it will not produce as good an oven spring as either a pizza stone/tiles or a screen when the pizza and pan are put in the oven. A lethargic, underfermented dough will behave even more poorly.
I might also add that if you want to use active dry yeast (ADY), you should proof it first in a bit of warm water (at around 105-115 degrees F) rather than putting it in dry in with the flour. If you want to combine yeast with the flour, you should use instant dry yeast (IDY). If a too-low temperature is part of your problem and you still want to use commercial yeast along with the preferment, you might want to increase the amount of commercial yeast a bit also.
Once you consider the above points and can rule out certain possible causes for your dough's underperformance, I'd be happy to put my thinking cap back on.
Peter
