Yeah this whole we can't win a Cup narrative against Lehner is pretty ironic considering all these people saying that probably think we could win with Fleury. Fleury has a long list of playoff collapses and hasn't won a Cup as a starter since 2009. FTR I think all you need is above average goaltending to win. It doesn't need to be elite. Most starters in the NHL are capable of that kind of play for a month or two. Just needs to come at the right time. Lehner from the the first 20 games of the season was more than good enough to win with, as was Lehner in the past two playoff runs. Fleury was also more than good enough to win with most of the time, but he had some EPIC collapses.
To your second point I agree this year is big for Lehner. I could see a world where if Lehner clearly falters they just move him for the cap relief and roll with Thompson next year. I don't think Lehner will be the reason we lose though. If we flame out in the playoffs again it will be because we once again can't score enough because we don't get bodies to the crease.
I agree you don't need elite goaltending, though my problem is that Lehner is below average, not above. Frankly, I wish they'd play a few games with Thompson and see if he's ready - barring a collapse we're playoff bound as the Pacific seems to be reverting to form as by far the weakest division. And yes Fleury has had a few epic lapses, he's also stolen a lot of games, which Lehner likely won't do.
To your point about not scoring in the playoffs, I think that is largely due to the PDB style of constantly just throwing the puck around the boards and behind the net (until scrubs like Koleslaw fumble it) and refusing to get into the scoring zones. Assuming Eichel, Patches, Stone, Stephenson and the misfits, we have plenty of guys able to score if we take the handcuffs off. And plenty of talent on the back end too - at least part of our defensive problems are due to teams not having to worry about our third or fourth lines scoring, which health will remedy.