Personally, I believe the game is straight dying. We know Place is experiencing burnout with this game, and to make matters worse, he's been looking for someone to take over for about a year now (it doesn't help that he has such a restricted hiring pool due to legal reasons.) Consistent updates can help keep a game fresh and keep players coming back, but with both of those previously listed factors applying, being burnout and no new developer, the game is not getting consistent updates. Along that, most updates are temporary events, leading to "dead periods" in between events where the game stalls out and begins to shrink in concurrent player-count before the next event, where it only spikes for a month or so. Stack that with a myriad of balancing flaws in weapons/items/zombies, an endless number of bugs, a prestige system that fails to fix the stale grind of the game from rank n/a-60, countless exploiters or rule-breakers in general with a mod-call system that can at times be slow (which is no fault of the mod team), the experience is going to become less enjoyable over time.