2687Wv3 have 2 cores disabled. At least I'd assume Intel uses the MCC dies for these. Also the TDP is more with respect to the AVX computations/turbo bins from what I understood.
But yeah, it's not a great product. 2687Wv2 was already a letdown compared to the original. I mean it had the clocks just like the 2667v2, but it was just not fast enough with only 8 cores.