Sir Geoff Hurst believes that Avram Grant was left fighting a losing battle following West Ham's flirtation with Martin O'Neill in January.
Former Hammers boss Grant, who was sacked immediately after the club's relegation from the Premier League, was expected to leave Upton Park with O'Neill taking his place.
Despite constant speculation over the Israeli's future, Grant survived only to preside over West Ham's nightmare end to the season.
And World Cup winner Hurst says Grant was undermined by the board's failure to take action and leave Grant a dead-man walking.
"During this season, the big mistake was trying to appoint a manager half way through," said Hurst, who was speaking at JABE's Football seminar.
"It became evident that they were looking at another manager and once that comes out it pulled the rug from under the manager.
"That didn't help and had they made up their mind to change then they might have got out of it. The only way it could have been different is if he had resigned because the club wanted him out to bring in a new man."