You can say that about many of the young defenders coming up nowadays. Actually, I feel that a new kind of central defender is coming up, and we are seeing an evolution that started out when Lucio was at his peak and when Makelele came into prominence.
In the past, central defenders just defended. All they did was sit back and defend. Nowadays, you see them get involved in the attack, linking up with midfielders and even going forward with the defensive midfielder(s) covering them. Nowadays, we see young defenders like Evans, Jones, Smalling, Hummels, Vermaelen, Koscielny, Pique, David Luiz, etc., come up who have good technical ability to go forward and good passing but are just an extra option and not really relied upon like midfielders are.
To say that such defenders should be defensive midfielders at this age is not a bad idea, but with the evolution occurring, I say let it happen. It will give teams more options in the attack, and for this reason, I say keep Evans as the central defender and let him be the extra man from defence to join the attack.