Let face it USS Enterprise D likley take all three BOP single handle if not for she defend the USS Enterprise C.
When USS Enterprise D fire five photon torpedoes she took about half one BOP shields since mordent damager likely somewhere between 45% to 55%. When USS Enterprise D fire all her phaser she destroy BOP when shield full strength. USS Enterprise D could photon torpedoes when charging fire her phaser destroy first BOP and fire photon torpedoes and phaser take out second BOP. Then USS Enterprise D weight for her phaser to charge and fire her photon torpedoes and then possible fire phaser and again take out the third one.
I have my theory Klingon Empire try hold on long as they could and one UFP starship made them have surrender a lot sooner. I like hear some other theories.