Ward has played 42 times for Rotherham, scoring twice and providing one assist, and is due back at White Hart Lane at the end of the campaign.
Warnock, who arrived at the New York Stadium in February, says the 21-year-old is "10 times the player he was" back then, though despite this he expects the former Chicago Fire and Coventry City loanee to be farmed out again next term.
"I don’t know whereabouts, whether Rotherham will have a chance or not, or whether he’ll go elsewhere.
"He’ll not get in the Tottenham team at the moment, he needs experience."
Another Spurs youngster, Alex Pritchard, has endured a difficult campaign having returned to White Hart Lane following a spell in the Championship with Brentford, and Warnock believes another spell in the second tier would do Ward no harm.
He added: "You don’t get much tougher places than the Championship. For example at Hillsborough (during March's 1-0 win against Sheffield Wednesday), in that atmosphere, I thought he did ever so well. He took a lot of pressure off us at times.
"He’s grown up an awful lot for a young man."