Norma,
For the benefit of those who are following this thread, the quote you recited comes from the PMQ Think Tank thread at
http://thinktank.pmq.com/viewtopic.php?f=6&t=8419.
I interpret the quoted portion to mean that a sponge (actually the consistency is more a biga consistency) will soften the final dough and, to combat this, the total formula hydration is lowered. That is why Tom specified a total dough hydration of 56% instead of the 58% hydration that you have been using. A classic biga with around 50% hydration will be a stiff piece of dough.
I took the dough formulation you posted in Reply 38 of this thread, at
http://www.pizzamaking.com/forum/index.php/topic,9908.msg86384.html#msg86384, with the 56% hydration that Tom recommended, and transformed it into the following threepart format set forth below. In this transformation, I assumed that the 0.1% IDY was with respect to the preferment flour rather than the total formula flour, and that the full complement of the total formula yeast, 0.25%, is used in the Final Mix.
Total Lehmann NY Style Dough FormulationKing Arthur Sir Lancelot Flour (100%): Water (56%): IDY (0.25%): Salt (1.75%): Olive Oil (1%): Total (159%): Single Ball:
 1601.05 g  56.47 oz  3.53 lbs 896.59 g  31.63 oz  1.98 lbs 4 g  0.14 oz  0.01 lbs  1.33 tsp  0.44 tbsp 28.02 g  0.99 oz  0.06 lbs  5.02 tsp  1.67 tbsp 16.01 g  0.56 oz  0.04 lbs  3.56 tsp  1.19 tbsp 2545.67 g  89.79 oz  5.61 lbs  TF = 0.08932 509.13 g  17.96 oz  1.12 lbs

Note: Nominal thickness factor = 0.088; for five dough balls for five 16" pizzas; bowl residue compensation = 1.5%
PrefermentKing Arthur Sir Lancelot Flour (100%): Water (50%): IDY (0.10%): Total (150.1%):
 533.68 g  18.82 oz  1.18 lbs 266.84 g  9.41 oz  0.59 lbs 0.53 g  0.02 oz  0 lbs  0.18 tsp  0.06 tbsp 801.06 g  28.26 oz  1.77 lbs

Note: Preferment flour represents 1/3 of the total formula flour (1/3 x 1601.05 = 533.68); the IDY is with respect to the preferment flour
Final MixPreferment (as noted above): 801.06 grams (28.26 ounces)
Remaining 2/3 of the King Arthur Sir Lancelot flour: 1067.37 grams (37.65 ounces)
Remaining total formula water: 629.75 grams (22.21 ounces) [Note: 896.59266.84 = 629.75)
Total formula IDY (0.25%): 4 grams  0.14 ounces  0.01 lbs  1.33 tsp  0.44 tbsp
Total formula salt (1.75%): 28.02 grams  0.99 ounces  0.06 lbs  5.02 tsp  1.67 tbsp
Total formula oil (1%): 16.01 grams  0.56 ounces  0.04 lbs  3.56 tsp  1.19 tbsp
Total dough weight = 2546.21 grams (89.81 ounces, or 5.61 lbs)
You will note that I treated the two additions of yeast separately. I could have added the preferment yeast to the basic Lehmann dough formulation instead, which would have changed the numbers slightly (actually, very slightly). But, I stuck to the procedures recommended by Tom.
In preparing the dough, you should have made the preferment as instructed by Tom and you should have used it the next day in the Final Mix along with the rest of the ingredients as referenced above in the Final Mix. Did your numbers mirror those given above, or something close to them?
Peter