Gardner has joined WBA from Sunderland.
New Leicester City coach Phillips told the Express & Star: "He was always great at getting goals from that advanced midfield position, but that means getting licence to get forward.
"Whether he plays in a midfield two and has a holding player alongside him so he doesn't have to worry as much about defensive responsibilities, or whether he plays in a midfield three, he is great at getting on the end of moves.
"And, if he gets into a goalscoring position, he is one of the best strikers of a ball I have ever played with.
"But in my opinion you don't get the best out of him if you play him as a defensive midfielder, on the right or at right-back."
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