No, I don't see Tavares as a 3C. He's been a 1C for years, and had some regression last year. It wouldn't shock me if he bounced back some this year. He put up 65 points last year, in a down year, at 17:52 a game. Jenner played last year mostly with Gaudreau, played over 20 minutes a game, and had 35 points, in 58 games. Jenner plays a rugged game, and has missed more and more time the last few years.
Jenner has played on a team devoid of C depth for years. He would have made an excellent 3C for a competitive team, but with reduced ice time, and reduced PP time his production would be around mid to low 30 ish points, in a full season... which is good for a true 3C... but in no world is Tavares going to be anywhere near that low.. We would love to have Jenner as a 3C, with Tavares as a 2C... that would be some solid C depth... but Jenner's shelf life, given the way he's played... his best before date has certainly past, and his game is likely to deteriorate pretty quickly moving forward.