The on-loan Aston Villa striker has been booed by Toon fans since his arrival.
"What you've got in Nile Ranger is a young lad who's done well in the period he's been here. He's come on and made an impact in games and I think it was more the fact that they were pleased to see Nile coming on.
"With Marlon it's something that strikers go through, it's about scoring goals. If I look at Marlon's general contribution, we knew when he came it was on the back of not having had a full pre-season.
"We're seeing in the games and in training that he's a player who will get stronger and stronger during the time that he's here. The most important thing is that he's on the side of a winning team that's at the right end of the table. The booing is nothing that concerns me."