You have no actual proof that either the D7 or BoP in the passage received any damage before engaging the Joyeuse other than wanting to believe that they didn't while I can clearly quote that the D7's staying out of the fighting till they engaged the Joyeuse.I did?
Your own quote makes it clear the first BoP the Joyeuse killed had already seen combat, and it still took two torpedo hits to bring down its remaining shields for a phaser kill
Furthermore?
The Joyeuse's command crew wasnt paying attention to the D7s after its collision with the BoP
In addition, the BoP that ate two torpedoes is also noted as a bogey (Bogey: (n) an unidentified flying object or radar target.), which suggests that it isn't the BoP that fired at them previously and prior to engaging the Joyeuse likely hadn't taken part in the fighting or it would have already been identified before it's approach like the D7's were rather than being initially marked as an unidentified ship.
"Aye Captain, aft phasers ceasing fire." Hadley checked his scopes. "The light cruisers are engaged at the center of the line. D7s still hanging back. Wait - we have a bogey coming up our port. Bird-of-Prey, they're going to overshoot."
"Ready tubes one and two, standby forward phasers."
The Bird-of-Prey swooped past the ship on the right, it's path curving across the bow of the Joyuese. The pair of photons launched almost simultaneously, a pair of cool-blue sapphires slamming into the smaller ship. The first splashed against the dorsal shields, but the second bled through the bubble with the effect of a hammer, the smaller ship's left wing jerking sharply down. Almost wobbling on its axis, the Bird-of-Prey flipped over to face the Joyeuse in a move that saw a scintillating blue phaser beam sweeping through empty space.