I don’t think Washington had anywhere near 30,000 troops during the Battle of Brooklyn. The British had about that number if not more.
When he 1st arrived in NY he had 19,000 with mmore troops coming in until the battle.
They were certainly not all high caliber
The English had 20,000 on Long Island but Washington had made the glaring mistake of splitting his forces and only had about 6,000 to face the entire British & Hessian force there