"The piano may be a bit of a crutch now," Paula said, "and that separates you from the audience. ... I want you to mix it up a little bit."
Simon disagreed, calling Paula's comment a "stupid thing to say."
"Elton John always used to sit behind the piano," he added. "Nothing wrong with that."
Later in the night, Matt Giraud performed Carrie Underwood's "So Small," also at the piano for the second week in a row. But no comments on his piano playing habits. Paula simply complimented his "authenticity" and Simon said he was "terrific -- one of the best of the night."