Nicholas made the damning claim ahead of the Hammers’ EFL Cup fourth-round tie against Tottenham Hotspur away from home at the Wembley Stadium in London on Wednesday evening.
While predicting Tottenham to win 3-0, the former Scotland international told Sky Sports: “What does Slaven Billic do? If he plays a strong team they could still be embarrassed.
“I'm a fan of Bilic but this is a really average group of players. He's partly responsible but I don't think you should judge him on a match like this.”
West Ham are struggling at the moment and currently find themselves level on points with third-from-bottom Everton.
The Hammers do have some good players and should be pushing for a top-10 finish in the Premier League table at least.
Players such as Javier Hernandez, Aaron Cresswell, Michail Antonio and Manuel Lanzini are wonderful and very talented, but there are others who are struggling.
Summer signing Marko Arnautovic has failed to live up to expectations, while midfielder Mark Noble is not playing well at the moment.
Much was expected of Joe Hart when he switched to the Hammers on a season-long loan deal from Manchester City in the summer transfer window, but the England international goalkeeper has been a disappointment so far the London Stadium.
“At this moment in time I don't think Slaven knows what his best XI is but when he does we will have a team that's very hard to beat,” The Daily Mail quotes Sullivan as saying.