Very though for them, maybe they are not doubting themselves again in the playoff. Last year Jamal is out and then Porter Jr has some extended injuries. But now, this season they are healthy, on top of the standings, but seems to be having problems closing out the regular season. And we might say that they are choking right now, in my opinion.
Currently, they lost 5 of their last 6 games and the only win that they got in that 6 game span was against the Pistons. They only have 11 games remaining, and it's a bit tough at least because on that 11 games, 7 of them are against teams above .500 (Warriors, Suns, Sixers, Bucks, Nets, Kings). TBH, I'm a bit worried on how the Nuggets are performing on their last games, but if they will manage to win majority of the remaining 11 games then I still think that they will retain that top spot in the West.
I understand that the Nuggets have been very inconsistent, actually very poor in terms of performance. But they are still at the top. The problem is as you said they have a lot of hard opponents going forward. It is going to be really hard for them to win in the next 11 matches because we have to keep in mind that the current form of the team is not good. It is actually simple, they will have to perform better. Unless they are going down in the standings.