Not entirely. The upper decks are not armored like the hull is. Shells CAN penitrate the upper decks as we are talking about 20th century weapons, and not 8 to 16 pounders that were shot from cannon and were round.

If you get a good enough fire going, and through constant bombardment, your DC crews may not be able to contain those fires. If any of those fires reach weapons magazines or fuel tanks........well it wouldn't be a pretty sight.

Even if you didn't sink the BB's, enough damage to the superstructure above decks would render her nothing more than a floating platform. She'd be out of commision for quite awhile for repairs.