I don't think they're so down on the deck per se, I think they were a little time crunched and didn't have time to analyze the deck. As Spikes they should never discount a deck simply because it doesn't appeal to their playstyle (I think this is true for Marshall, not so sure about Jon). UW Heroic is strong in the current meta, but it hasn't put up the same consistent results as Abzan.
On the whole the most recent episode felt a little inconsistent, Marshall is really coming off as the expert of this standard format (between he and Jon) - he's certainly commentated on enough to see the evolution of the format. I was surprised that Jon admitted that he doesn't watch coverage, it also felt like Marshall was reporting to Jon about the deck-lists, but Jon, having not seen how the match-ups play out, can't really offer any meaningful insight.
I've been enjoying Mike Flores and Pat Chapin on Top Level Podcast - all their credentials aside - I think they're offering some very high level analysis. I love Chapin's discussion of the micro decisions that go into adapting the Abzan list for each tournament, I also like they're grounded discussion of specific cards and how they affect deckbuilding and playing.
I came to CR from LR, I think it's a great cast. The show is at its strongest when Jon is playing standard (or at least watching matches of magic), or when they guys are talking about specific aspects of the game (mana, sideboarding, etc). I think that a successful tournament analysis would require both of them to watch the matches (not just Marshall) as a ground for their analysis.
Kudos to Marshall - he's been working his tail off these last few weeks and is still putting up great content for the community. I think Jon should find a night a week to stream standard or follow coverage; I understand this is diffucult (especially with his job), I'm just trying to think of constructive and sensible ways that he can level-up his co-host role.