I've been playing since alpha. Lemme offer some thoughts:
As EurasianJay said, we have a major issue with player retention. This is already evident from the Discord: if I check in once every week, I can see a totally different group every week...but the old group is nowhere to be found. Lots of other former players have left the game; I personally know a lot (see if you remember them):
-Bogdan (OG DuelystDB)
I think Duelyst "peaked" during Shim'Zar, because the game was not only so fresh but the expansion award something worth being hyped for. That being said, this game has a serious player retention issue; no matter what excuses you can come up with, Steam numbers are dropping, and this is only symptomatic of a larger issue.
How do we solve the issue of player retention (or lack thereof)? I don't know. I personally left because the meta was so stale to the point where the first 3 turns of any game were practically the same thing, with the same minions, same spells, same positions. Bloodborn only made that worse, with bullshit cards like Meltdown, all the while CP seems to have a fetish for making Vanar the most powerful faction possible.