Stamkos played right wing with Cirelli at centre. Even if he went back to centre, I'm not sure he'd be a 1 anymore.
Richards and Carter were good 2s, but they aren't 1s.
From 08-09 to 16-17 among centres Jeff Carter was 3rd in goals, 16th in points, and 22nd in points per game among those with 100 gp, while being a strong two way player.
Richards on the other hand did fall off after Philly and was just a strong 2C.