Allardyce told reporters: "We were off form but Southampton were a good team on the day and every game since. I think we have had the kick up the backside and the lads have responded brilliantly to that disappointing performance.
"We had to wait a long time to put that right - we had to wait 16 days before we played Hull City away after the international break. Players like Enner Valencia and Cheikhou Kouyate played two games in that time so our response has been very good.
"It has been a good reaction. We have looked at the players and changed the system and it looks like they are very adaptable to different ways of playing which is nice for me."
West Ham face Manchester United in their Premier League match later today.