The Kilo-class submarine and the landing ship (which was being used to transport equipment and supplies) are probably both BER. Currently, they obstruct damaged drydocks, which lessens the usefulness of Sevastopol as a naval base. Whether or not the admiral commanding the fleet was killed in the strike on the headquarters building - Russian has claimed he is OK,
- many senior officers were killed, and the building is no longer usable. It doesn't garner a lot of coverage, but Ukraine has been picking off Russian radar and SAM sites protecting Sevastopol and Crimea (the attacks on the two ships and on the HQ probably exploited holes created by reduced radar and SAM coverage).
All this taken together, it was prudent, and probably well overdue, for the Black Sea Fleet to pull back to Novorossiysk. This base, too, is not utterly safe, but far fewer Ukrainians assets can reach it. So far. It says a lot about Russians' technology and how thinly stretched they are that they could not "simply" beef up protection of the Sevastopol base.