Honestly these prospects are all fine. I have nothing against any of them. They may have good NHL careers. I think realistically though, many would say they probably aren't Top 100 drafted prospects, or fringe at best, at the moment. Really these are the kind of prospects that teams should have already in their system in the ordinary course of making draft selections and watching players develop. And when a new wave of first round picks are made in a few months (of which Pittsburgh likely won't have any, or at best a 31st/32nd overall pick), that'll push them down further.
So they're basically recouping where you'd expect them to be in terms of adding prospects to the pool, but that Pittsburgh isn't from all the recent years of trading picks (mind you, less of a big deal when they were winning Cups, but the earliest any of these players were picked was 2020, a year the Penguins lost in the Play-Ins). I don't really see the Penguins as some cheap graduated prospect depth away from anything at the moment to be honest.
This just feels very "gotta do right by Crosby, gotta do right by Crosby" as far as getting prospects that may be able to come in and give cheap depth and try to salvage something as far as getting into the postseason for as long as Crosby (turns 37 in the offseason) is present and productive.... when given where the Penguins are in their cycle, I'd have much preferred them to be adding draft capital than drafted 2002-2004 birth prospects. I think amongst the prospects you're probably looking for a positive outcome where by the time you get to the post-Crosby years, these are the kind of players you can flip for draft capital at that point. I'd rather just have the draft capital right now for Guentzel, who was your best trade asset, and build a more timeline appropriate prospect foundation for when you do hit your eventual tank years.
Anyways, that's my 300-foot overview of the situation from their perspective, not getting into the whole "good value, expected value, terrible value" hand-wringing about what a rental is worth.