Yet Redknapp has seen enough of the 22-year-old in Tuesday's 1-0 win over Fulham to believe newly-promoted Derby will feel his full force at Pride Park on the opening day.
"I think we will see Sulley at his best on the opening day of the season," said Redknapp.
"He has got everything you need to play in the Premier League. He is strong and aggressive and he did something against Fulham you very rarely see anyone do these days in that he lost the ball, then chased back 25 yards to get a block on the full-back.
"Most players in that situation would start feeling sorry for themselves. Not Sulley. I think he is going to be a massive player for us and a real fans' favourite."