The Hammers are currently 12th in the Premier League table on 37 points, compared to last season when they finished 10th with 46 points.
"Last season was an overachievement but this season has been an underachievement so far," Allardyce told reporters. "We're always learning and looking to evolve.
"We have to stay resilient, perform at a high level and get points on the board. It's important to do that against West Brom [on Saturday]."
West Ham have three games left in their campaign.