Roo wasn't at his best and he still led the side in marks per game, was 3rd in goals per game, 3rd in marks inside 50 per game, 4th in score involvements per game, 5th in tackles inside 50.
I agree that by the end of the year he was basically a non-contributor, after Maddie's Match he was cooked. But saying he had no influence suggests you didn't watch or don't remember games in the first half of the year. Paddy has never kicked more than 2 goals a game and he's under a serious injury cloud that ends careers. I hope he does well in 2018 but he's nowhere near replacing what Riewoldt put out this year and an unthinkable distance from replacing Rooey at his best.
As for Joey, he was 3rd for disposals per game, 2nd for effective disposals per game, 2nd for uncontested disposals per game, 4th for rebounds per game, 2nd for metres gained per game.
Again, not at his best, but that's a lot of stats to replace. Of course he had influence. Pretending that White (some promise but only 4 games), Rice (0 games), or McKenzie (16 games but doesn't look impressive) could possibly somehow replace him in 2018 is just a fantasy. Savage could probably but at best he's as good as Joey was this year, he's certainly not streets ahead.
Agree that both Armo and Steven should be better next year, that's all upside. But we lose a lot with Rooey and Joey. If you're telling yourself otherwise then you might have a disappointing 2018.