Van der Vaart's latest moan came after he was asked to play on the wing for Spurs in Sunday's 2-1 win over Arsenal, in which he scored.
Redknapp snapped in The Sun: "Yes, it does seem to be a problem. Rafa can't run back and chase the full-back. Against the better teams it is a problem.
"Rafa's best position is in the middle, playing just behind the front man.
"The only problem is that Jermain Defoe plays there too and Jermain is playing very, very well at the moment.
"So, I guess I have got a decision to make, haven't I? I suppose it's now between Rafa and Jermain over who plays in the team."