Just been perusing the results from yesterday and looking up the palmares of some of the other riders in the breakaway group...
Michael Rodriguez finished nearly 8mins behind Gesink on the stage to Mt Baldy in last year's Tour of California, and was 29th overall in the mountains classification, so the evidence on paper suggests you may be overrating his climbing ability.
Van Rensburg won the Tour of Eritrea last year, and I dare say that's a fairly bumpy race, though the standard of competition won't have been all that high. Will be interesting to see how he gets on today.
Enzo Moyano looks like he can climb a bit - he did OK in the Tour de San Luis last year - but probably not a real threat. Josef Cerny and Pavel Kocketkov also look like competent but not great climbers. Nicola Dal Santo and Xu Gang look like they aren't worth losing any sleep over.
Of course, this is all based on past results rather than current form, and who knows what the circumstances of those results were - I mean, if you only look at his results on paper, Siutsou has had a poor season so far... I don't claim to know what any of these riders are capable of when fired up. But suffice to say I would be surprised if any of the riders in yesterday's breakaway figure prominently in the final reckoning.
Edit: in light of the Siutsou thing, I had a closer look at Rodriguez's results and he was probably riding as a domestique for Duarte at the Tour of California last year, which puts his result on Mt Baldy into some perspective.