The France international appeared to represent something of a coup for the Hammers last summer, with the highly-rated midfielder having been linked with a move to England for some time.
Things did not work out as planned for Diarra, though, as he found first-team football hard to come by.
Having aired his frustration, he was then loaned to Rennes during the January transfer window.
Diarra has now suggested that his move to Upton Park was driven by agents, rather than Allardyce, and that he was left with no choice but to look for regular game time elsewhere.
He told France Football: "In London, I knew that I had no guarantee to start games and I knew there would be competition, but I was not told that I would be a reserve.
"The coach did not refuse my arrival, but he didn't want it either. I was just one additional player.
"I never gave up, but in the end you get fed up of fighting for nothing.
"Maybe that is why the officials granted me a loan. They understood that I was no cheat. A lot of players could have just waited for their cheques, but I won't do that."
The 31-year-old added: "Should I have spoken to the coach before I signed? I wanted to but he was always at training.
"I was handed a three-year contract, but he (Allardyce) wanted to work with his own players that have followed him for years.
"It is one of my worst memories because I have been cheated. I could not accept the situation any longer and went to meet with my representatives. They understood and I thank them.
"I have turned the West Ham page until the end of the season, because I have been loaned with no option to buy."
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