The Mexico international has struggled for minutes this season under Redknapp.
"He is on the bench, he has got great ability, we nearly sold him at the start of the season for £13million to Udinese," Redknapp said.
"The chairman of Udinese came over and had a chat with the chairman and he wouldn't go and that was a lot of money.
"Gio is a good player and is a good lad. He has good ability but in the end his contract is gradually running out so I don't know what you'd get for him in the end.
"I don't think he wants to sign a new one so I think the £13million would have been a good deal."