McPhee reminds me of Gainey. A respected hockey mind that had his reputation tarnished because they got desperate and made a very shortsighted move.
I don't think either men are deserving of scorn.
Imagine next year Vegas players largely regress to career norms. Say their D becomes a #2 (Schmidt), #3 (Miller), and then a bunch of 5-6s. That's Green, Poti, and all the caps D in the first 8 years of Ovechkin. Green is the only one who was able to stick in the league for more than a year after leaving the caps. Now imagine McPhee keeps going with these guys for the next 10 years without ever signing or trading for another top 4 D, with the only chance of getting one is Brannstrom or some future draft pick developing into one.
Next, imagine Marchessault/Karlsson/Smith continue being high end players, maybe even get better, but Haula regresses to a 3rd liner, Eakin to a mediocre 3rd liner, Perron leaves, they sign Neal but he's a ~30g-55p player, Tatar and the rest of the roster except for Tuch regress as well. Now imagine that you have Haula/Eakin be the 2C for the next 5 years until Glass takes it, with mediocre rentals like Sutter or super old ex stars like Thornton acquired to plug the hole for some deadlines until then. Your 2nd line gets dominated over and over in the playoffs despite Semin's (Neal's) best efforts because other teams have a clear center lane and nothing's done about it.
That's McPhee with the caps, content with having the same holes on the roster unplugged for a decade with the only hope of having it go away is someone like Kuznetsov, Orlov or Carlson completely blowing away their draft expectations years and years down the line. McLellan probably isn't nearly the hockey mind McPhee is (his drafting is much less impressive) but he's a lot more effective than McPhee was simply because he goes and gets a solid, if not perfect solution as soon as its needed, be it an esteemed veteran defensive D who can bark at the bench (Orpik) or established high end 2 way D (Niskanen), versatile gritty veteran top 6 winger (Oshie & Williams), 3C (Eller), high end PP defenseman coveted by division rivals (Shattenkirk), bargain basement mobile LD in his late 20s to stabilize D corps (Kempny). Only prospect's development McLellan really leaned on was Kuznetsov, all the other guys (Wilson, Burakovsky, Vrana, Djoos) are a complimentary nice bonus pushing the team over the top rather than absolute core players leaned on for carrying a major load.