OK... this is absolutely ridiculous. I've got no chance against players running quad cannons. They rip through my shields like they're paper. Dual heavy cannons don't do nearly that kind of damage. Before today I could tank against escorts no sweat... now, no way. I realize it's pay2win now, but this is ridiculous.
Double check your skill tree. With the new skill changes, the ships do have slightly different performance variances. Before the new skills (and specced for Adv Hvy Cruiser Refit) , and power settings,consoles etc I had a turn rate of 17.1on my T5 Excelsior, now its a 16.3 (which I found a way to up it ). You might have set up the skill tree in a way that isnt so tanky. With my current weapons set up for my tac' Excelsior, I took a few peoples shields down on the first volley as well (no quad cannons here).