The Dutchman fired the opener against the Black Cats with a smart finish on 16 minutes and laid on the third for Wayne Rooney after brilliantly skipping free of two Sunderland defenders.
Van Persie has been a revelation since he arrived at Old Trafford in the summer and his team-mates say he is a joy to play alongside.
"Robin has been incredible since he joined. He's a fantastic player," Jones told MUTV.
"He went straight into the firing line after he arrived and has scored a lot of goals. And he's such a nice lad off the field as well, so it's great to have him here."
Smalling echoed those sentiments in an interview with MUTV: "He's really making the difference.
"He only came here in the summer and didn't have much of a pre-season so it was a case of just getting straight into the games, but you can see in every match he plays that he's such a threat and he puts teams on the back foot. His understanding with Wayne [Rooney] is growing all the time."