One of the better internet analyst (Mahaney) is projecting Yahoo's core business valuation to be about $10B.
Any of the recent gains are still attributed to Alibaba. (They have had monsterous shopping season. And the biggest shopping days are still to come in China.)
The holiday quarter should be the watermark. Design changes were in place and numbers should be improving. If the street starts to smell improvement, the core business valuation has lots of room to move.