This is a real undervalued gem right now. It used to be in the top 20, have no idea why it's gone down. Development has been solid, and their smart contract and TX/s capability is much better than ETHs, it's essentially a better version of ETH. I think Waves will take off again soon.
The possibility why waves drop their ratings on the market cap is all because of the newly hyped and pumped coins which overtook some of the positions of the good coins out there if you will observe the top 20 coins right now some of them are newly created coins or some unpopular coins, got hyped or pump by some groups of whales to attract investors, that's their common way of making such coin more famous and costly.
It was truly undervalued a few weeks ago, and even now it is still at an excellent price. Anything below $10 is still a great value buy though even at 12 I would still be adding more and more to it.
It has certainly dropped off the ratings, as you say because of other alts that have been strictly overvalued. Waves may be taking its sweet time to develop as a platform but it has so much in store.