I'm going to say no because not of Fleury, but they started to dismantle a Stanley cup winning team. Fleury was not going to make up defensively the loss of Bonino, Daley, Cole, Kunitz, Kuhnhackl and more along the way.
Too much got pined on Rust, Murray and more that they were elite players and could bridge the gaps.
So, the Pens were not winning another cup because they were swinging to not being who they were. Calling for a 3-peat while still shedding integral players and not replacing them is why they were not winning another cup.
They still haven't and why they are 1st round fodder.