Cullen ended up leaving West Ham to join Charlton Athletic on loan for the season, as he wanted game time.
But the youngster insists that he was not forced out, as Pellegrini told him that he was prepared to allow him to fight for a place.
"I needed to be playing games,” Cullen said.
“Manuel Pellegrini was very supportive of me, saying I could stay around and try to push for my opportunity. But I couldn't hold on to see how results went.”
West Ham have had problems in central midfield, but it is questionable whether Pellegrini would have turned to Cullen, even he had still been around.
Cullen has proven to be a standout performer at League One level, but at levels above that he still has a point to prove.
The West Ham youngster has played just one game for Charlton since joining so far, where he helped them to a 2-1 victory over Southend United.
Cullen was also on the substitutes’ bench for West Ham in their Carabao Cup tie against AFC Wimbledon earlier in the season.
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