Another thing lost in all this is, aside from blowing a hole in the defense and asking more of players in terms of matchups, they would need to find a way to replace Pietrangelo's offense. Going back to the beginning of last season, Pietrangelo is tied with Schwartz for 4th* in scoring amongst Blues players; both have 93 points with Schwartz in 1 less game
*Tarasenko almost assuredly would have leap frogged both Pietrangelo and Schwartz if he had played more than 10 games this year.
Most people point to Faulk and say "well he can replace that offense!" and I really don't think that's the case. Faulk has outscored Pietrangelo one time over the course of his career and that was by 3 points in 14-15. In 2015-16 Faulk and Pietrangelo both produced 37 points -in fairness to Faulk, he did it in 13 fewer games- but since then Pietrangelo has produced more offense while being miles better defensively. Since 16-17:
Pietrangelo- 299GP 58G 195Pts
Faulk- 302GP 41G 119Pts
That gets worse considering that for most of that time Pietrangelo was playing the very role Parayko is now in while still putting up high-end offense. Even if the plan is to just feed Faulk easy minutes and matchups in hopes he can find new offensive highs, someone still will need to draw the tougher matchups outside of Parayko and Scandella (despite the belief Pietrangelo is now sheltered nearly 33% of his TOI is still against what PuckIq considers "elite"). It's not dramatic to say without Pietrangelo the team goes from a contender to merely above average immediately given the impact he has at both ends of the ice. The Penguins won recently with worse d-corps than what the Blues would be rolling into next season with, but the Blues don't have anywhere near the talent up front that those teams did.
While I agree Faulk doesn't replace all of Petro's offense; IMO the bigger problem is actually the #2 LHD.
I'm not convinced Dunn can handle top 4 minutes from a defensive standpoint.
I love Boom Boom, but he brings nothing offensively.
Mikkola is unproven and looks to have very little offensive upside(could turn into a great stay at home type, but I doubt he cracks even 20 points on a regular basis).
Perunovich also unproven and looks to be in the Dunn category(questionable defense, especially at the start).
I tend to agree with the thought that Faulk can fill a lot of the roles that Petro plays, but one thing I don't see him doing is producing enough to carry a defensive liability or offensive blackhole next to him.
IF we could somehow swing something to get a decent LHD to go next to Faulk, I think we'd be perfectly fine(and we might be able to massage the cap to make that happen), but I don't think you can expect Faulk to do it by himself.