Hammond has returned to his hometown club after signing a one-year loan deal with Brighton from Southampton.
Poyet told the club's official website: "He knows the club, he has experience, he has presence and he knows the division. He's a winner and he has quality.
"We have a lot of quality in our midfield. We need that presence in midfield. The fact it was Brighton helped him make a decision. It's important that the fans know how much he wanted to come back.
"He is a real man. We wanted that extra experience and presence on the pitch and in the dressing room. He shows what we were looking for. We didn't know he was available and as soon as we knew there was a small chance we went for it and waited for it to happen."