Mika clearly views himself as a shutdown center. Unfortunately, he's also a student of Rangers hockey, meaning that shutdown centers are modelled after studs like Barclay Goodrow, Nick Bonino, late-career Derek Stepan, and Kevin Rooney.
I believe he's a victim of his own success in this regard. The worse he plays, the more he's affirmed organizationally as a two way success. And as long as he keeps getting his special teams points, declining offense isn't really a legitimate criticism when viewed from inside the organization.
@Ola said for years that he saw Mika long term as a winger, and I'm coming to agree with him more and more. The rangers should stop looking for a 1RW and start looking for a 3C, since they're stuck with him long term no matter what.