Smedley, who has no joined Massa at Williams after being placed on gardening leave, believes his long-time colleague is better off since the switch.
He told Autosport: "He's a very, very good driver and he's been given the freedom of head space here to do what he's paid to do, and he's delivering.
"I see Felipe now very relaxed, incredibly experienced, there's a maturity about him and he carries that very well."
"He understands that the job he has to do here is not just about driving the car, it's about driving the people as well."
Massa finished 15th at last weekend's Chinese Grand Prix.