Just do some basic math... 621 points over 9 years = 69 points on average. He also has a career +/- of -42. That's putting a lot of pressure on the back end, because when he ain't shooting on the net, he ain't playing.
Also, what exactly are you basing the "better than last year" on? They lost a lot of guys that got them to the final, so how on earth can you qualify that except as a guess? I don't know if they're better or worse than last year, a whole lot depends on how matthews is going to like not being the star. I mean he had a temper tantrum at the end of last year, how is this going to improve that? Marner is a bit of a loose cannon, he might or might not show up.
I will say they might do better than they have in the past few years, but likely nothing better than the sudin years. Sure some playoff appearances, but not enough on the 3rd and 4th lines to go deep in the playoffs. They -never- have enough to go deep in the playoffs.
As for the marlies...the leafs have a very annoying habit of getting good players in the farm, but then trading them off. Remember pogge? He was going to be the saviour of the leafs, I don't think he even played a single game in the big show, they traded him off to siberia or something like that. Marner is one of the few exceptions, oh and I guess kadri, although as a 34 point per year average, he's at best a 3rd or 4th liner (that they keep putting on 1st or 2nd for who-knows-what reason). I don't know as if marner even played in the marlies, I think he got picked out of the OHL direct. I think I read somewhere that the leafs have a phenomenal farm system, but that they don't recruit from their farm enough. Again, because they want the big flashy names to bring in the crowds.
So I'm just saying there is no way to know if this new mesh is going to work, it may, but it may implode spectacularly. I'd need a couple of months of looking at how their 3rd and 4th lines play before saying they are good or bad. Blind faith in a team is what led me to be a leaf fan for so many decades. I know their tricks, I know their habits, and unfortunately I think I know their future.