The Hammers were beaten 3-0 by the Saints at London Stadium which was their fourth league defeat in a row and fifth in six Premier League matches this season.
"If I'm honest, it could have been six in the end," he told Sky Sports after the match.
"On the bright side I don't think it can get any worse.
"We've conceded 11 in three games and it's laughable, and it's not good enough. We know that."
The loss has West Ham sitting in 18th position on the table having already conceded 16 goals so far in what has been a very mediocre beginning at their new home.