Imo if he was a playmaker is agree with you. But he's actually kind of bad at it as evidenced by his play on the marleau line and on the powerplay. He's setup to be a goal scorer but as of right now he needs someone to get him the puck in scoring positions. Nothing wrong with that but I say to be a top six center he absolutely needs to score goals.
Well, when he was playing center, he wasn't playing with any real playmakers so that probably attributes to the lack of goals. However, he was showing plenty of effectiveness as a center with lots of different things he was doing well. His faceoffs, his possession numbers were good, his board play was good, his puck-handling, and scoring chance creating were all good.
To be a top six center, sure he needs to score goals but that wasn't the role he was playing until parts of when Couture was out. In the 3rd line pivot, he was a very effective center even without the goals that some people are so fixated on.