Porter, 28, made 44 appearances for the Blades last season after arriving on a free transfer from Derby in July 2011, but nearly half of those were from the substitutes' bench as he played second fiddle to leading goalscorer Ched Evans and Richard Cresswell and he scored only eight goals.
Wilson said: "He's not showed us everything he can do in my opinion. He's still got a lot to offer and at this level he is a massive handful.
"From this year on he understands exactly what we want from him. His fitness levels are fantastic, he's as fit as anybody at this club, but I don't think he pushes himself hard enough at times.
"But it's a great opportunity for him this year and I'm delighted he's signed because he can score us goals and he can create goals for other people, particularly his partner who plays up front with him.
"We saw glimpses of him last season, but glimpses is not enough, we want consistency and this what we're trying to work on. He hasn't played a lot of games for one reason or another, but he has the capacity to play consistently well and that's what we're hoping for this season."