I feel Roy lows or gap with vs after Montreal career could be overstated a bit here.
Older Avalanche Roy has a good argument to have had the best nhl goaltender career from 1996 to 2003, 2cup, 2 Smythe worthy run with an actual Smythe.
.917 in the regular season during that window was pretty much second to only Hasek (the only guy but very solid and winning argument to have had a better goaltender career during that window with the cup, the final, the gold medal, the harts):
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Hasek..: .926
Roy....: .917
Hackett: .913
Burke..: .913
Brodeur: .912
Most playoff win by a mile and his .922 in the playoff is in that too close to call top tier of that era:
Hasek..: .929
Kolzig.: .927
Belfour: .925
Roy....: .922
Brodeur: .919
Joseph.: .918
Making team Canada in 1998 felt natural, would he have took the job without special condition in 2002 we would have had no goaltender controversy instead of the Cujo->Brodeur situation...
His competition got better, but not playing for MTL did not expose him or anything and he was more than good he was probably the second best goaltender in the nhl having about the best results in the nhl, without a freak like Hasek establishing himself Colorado Roy would still have been for the 96-03 been considered the best in the business and the one you pick for a playoff run, not by a gap (when he faced Belfour or Brodeur in a playoff series felt a bit like wash, but still him).
Roy never had a negative GSAA season and after his first 2 season or a lockout year, was always 13 or above.
I am obviously not saying Roy was a bum after the early-90s — to be clear, he was one of the best goalies in the League up until he retired —but he was never as strong again as with Montreal from ages 22 to 26/27. Really, not even close.
1987-88 to 1991-92 (RS, and min. 110 games played):
.909 Roy
.899 Belfour
.898 Essensa
Patrick was clearly, I think, the #1 goalie in the NHL during these five seasons (although he didn't win a single Cup).
Now, you'll notice he didn't have
such a great season in 1992-93 (4th best save%, 7th-most GSAA). Overnight, he went from #1 League dominant goalie for the past five years to just very good goalie (stopping shots at the same rate as past-prime Fuhr and Bob Essensa). Why is that? Had Roy eaten too much poutine in the summer of 1992? No, my guess is it happened because Montreal shifted from the defence-as-first-and-only-priority coaches that Patrick had enjoyed, to date, throughout his career to a coach who wanted a balanced line-up with about three offensively attacking lines (Jacques Demers).
Patrick then had a great playoff (despite Montreal facing relatively weaker teams) and a nice 1993-94 season. In 1995, he was nothing special, and in 1995-96 he was moved to Colorado.... then the #1 team in the NHL. He received no Vezina votes for either of these two seasons.
His seven full seasons in Colorado, his Vezina finishes were a solid 2, 3, 4, 5, 5, 6, 8, which is great but not transcendent.
For the whole period of Roy's Colorado era he ranked 4th in save percentage, which is of course really good... but he was only stopping pucks at the same rate as Roman Cechmanek, Manny Legace, and Jeff Haket now that he wasn't shielded by the League's best defence every year (not unlike the 1992-93 and 1995 seasons in Montreal). It was a goalie-dominant period, where statistically negligible differences separated future Hall of Fame goalies from ones we remember now as also-rans.
(I don't really get too deeply into playoff stuff for comparisons, with goalies. I think it's a lot harder for a star forward to score, say, 35 points in the playoffs than it is for any #1 goalie on a playoff team to get hot, with a lot of team help, and end up with Conn Smythe consideration.)
I guess my concern with the Brodeur / Roy thing is that people love to take the argument that Brodeur's success was partly due to his team's construction and system... but I rarely hear this applied to Roy, who may have been (other than Ken Dryden) the single luckiest goalie in League history in terms of team positioning — first in defence-only Montreal, and then (just at the moment all goalies suddenly started looking dominant) in super-strong Colorado.
Patrick was certainly one of the all-time greats.... but he had his embarrassing diva moments and playoff meltdowns in big moments...
and he lost multiple playoff series to Mike Vernon.