Yeah, Jordan Staal and Martin Hanzal are third line centers. They may be playing higher up in their respective lineups, but to me, Staal is a second line center and Hanzal is a first line center like Tyler Bozak is a first line center.
Now, Jordan Staal is a very good third line center, mind you, but I have difficulty recognizing him as a top-6 forward when he's only cracked the 50 point mark once in his eight year career, and when he put up 40 points in a full 82-game season last year.
As for Hanzal, there may be cause to rate him as higher than a 3rd liner, but scoring at a 50-point pace for the first time in his career at the age of 26/27 over the course of a 65 game season last year won't do it for me. Not after he's failed to even crack the 40 point plateau for the other six seasons of his NHL career. If you want to call him a legit top-6 forward, he's got a lot more to prove, unless we all want to join hands with Dave Nonis and start proclaiming that David Clarkson is a top-6 forward.