Striker Michail Antonio says West Ham have tried to change their "philosophy" to compete for a Champions League place but the "transition into a big team" is not working.
David Moyes' side are 18th in the Premier League and have not won in the top flight since 24 October.
They spent £160m in the summer after qualifying for Europe in back-to-back campaigns.
Antonio says their recent struggles are a consequence of the past two seasons.
"I feel what we've done over the last two years we've thought, 'let's not get complacent, let's get our 40 points'.