Short answer: 50-100 basis points less than the S&P 500 rate of return.
Longer answer: If I'm being frank, a financial planner should have explained their value beyond investment returns. If they sold you on investments then you should pick someone who takes your whole financial picture into account. Investments is just one piece of a large puzzle.
To directly answer your question: I would say expect them to lag the S&P 500 by 50 basis points (.5%). If he exceeds the market then that is just gravy. This is tough since, statistically speaking, most investment managers won't perform better than the market in the long run.
A financial planner's value add is called "advisor alpha" and a Vanguard study states that a financial advisor can have a return on your money up to 3% IF they are managing your money holistically. Here's a link to a financial planning mag article on advisor alpha (3% Advantage?).