I think I have a pretty good read on what Miller is. Let me know if you disagree somewhere here.
He is going to play with Pettersson / Horvat for all of next season unless something really peculiar takes place.
The questions I feel we need to ask are;
How many points MORE is he going to score than who he is replacing on those lines?
How many more wins should we expect as a result of the added scoring?
My guestimate is ~15 points. I dont know where you fall with this. And that would result in, what, 3 more wins?
To me he really does not move the needle for Canucks.
Then let's look at this in depth and see what we should expect.
Our top six last season had all kinds of players in and out of it, so let's just slot Miller in alongside Petterson and Boeser replacing their most common linemate with him. Those linemates were Leivo (24.61%) and Goldobin (14.03%) when averaging between both players even strength TOI stats while together. Other line-mates for that pairing don't add up to equal Goldobin's percentage so I ignored them. Leivo scored at a 30 point pace for us last season while Goldobin scored at a 35 point pace. We gave Lievo 15:57 TOI/game last season, so let's give that to Miller instead and see what that works out to.
Miller's last 3 seasons saw him scoring 2.59, 2.51, and 2.50 points per 60 minutes in 14:40, 17:01, and 16:22 TOI per game respectively so it seems like his points per sixty stay consistent even in increased ice time. Plugging the average of those P/60 values into a TOI per game of 16:00 we get an expected points production of 55 over an 82 game season. That's 20 more points that Goldobin and 25 more points that Leivo.
For people concerned with his goal scoring after last season's total, he's usually a 0.985 G/60 player and even with last years average factored in his a 0.89 G/60 player. That translates to a 19g - 36a - 55p season which would make him our 4th best goal scoring winger, as well as our 4th bets, points producer if last season's totals hold true again this season. That bodes well for our top two lines, especially if Pearson can continue the pace he was on over his quarter season with us.
With no assumed growth from Pettersson, Boeser, or Horvat and continuations of their usual paces for Miller and Pearson our top 5 players will be on pace for 76, 69, 61, 55, and 43 points respectively. One of Leivo or Goldobin will likely round out that group though Roussel or Baertschi would both add another 40+ point pace player into our top six if one can match his pace from last season and the other can finally stay healthy for a season. Ideally, we'd look to add another top-six winger to that mix and see some growth from Pettersson and Boeser to really increase how potent our top six is.
As it stands those PPG paces would have our top six sitting at 43rd, 59th, 78th, 100th, and 157th for the 5 players listed with the 6th player likely being around that same range. That's a solid top two lines worth of production if we get a little health and people can play to their careers average levels.
Given all this, I think JT Miller will move the needle a fair bit and make our top six far more respectable this season than it was last season.