Yes,you are very correct.West Ham was one of the teams that I admire alot in the premier league last season and also this season,they have shown consistency in this two seasons,qualifying for Europa league last season and are vying for that same spot this season.
They have dropped form maybe because of fatigue, or injury which are the main factors in the lose of form from any team.But I believe they will still work on their form to gain their momentum back.
some other teams started the season badly, but they warmed up in the middle of the season. so teams like United and Arsenal get points to catch up.
while West Ham started the season well. but they have decreased performance. Maintaining good performance will certainly be very difficult if there are more and more matches in several competitions.
West Ham should have enough good players on several fronts. especially the rotation of players when they have fatigue and injury problems.