Oh, I'm not forgetting the shields were down.
Even with the shields down however, the Enterprise-D should have destroyed a measly BOP, suffering little damage in the process.
Sloppy writing was what allowed the BOP to inflict as much damage as it did.
What did we see in Generations with Riker in command?
One measly phaser shot which did some damage to the BOP shields.
Why not fire 10 torpedoes in a Sierra pattern along with a full-out phaser barrage instead and turn the BOP into minced meat?
Did the BOP's shields suddenly increase by a factor of 100 allowing their to be invulnerable completely while also dumbing down Riker and everyone else on the Enterprise-D?