Price of Nxt since september (in BTC) has dropped about 33%. If calculated from December 2013, it's about the same.
The cap dropped together with BTC.
The drop from 3 to 8 or 9 also is due to the rise of both XRP and BTS and Stellar.
So instead of dropping, we've been overtaken, which is something different. Your explanation didn't allow for the new players in the top 10.

Otherwise, referring to the post above.
I suppose we can both cherry pick dates. So NxT is either languishing or capitulating depending upon the date selected in relation to BTC.
Dropping in market cap is a sign of another type of death, losing market/mindshare which is worse than price.