Are User Stats Relative to SERP Position?

I think you may be right about every click bringing more frustration - and a more likely bounce.

But I don't think your assumption that Google uses bounce rate as a ranking metric is accurate. That's what several members here have conjectured, but several Google spokespeople have repeatedly said that the basic bounce rate is too noisy a metric for the algorithm to use.

If there's anything close to bounce rate in the algo, it's some combination of bounce rate and time on page (dwell time). In fact, the Google Analytics blog just published an article about how to get an adjusted bounce rate, where a time-on-page over so many seconds (your choice on how many) means that a bounce is no longer counted as a bounce! See Tracking Adjusted Bounce Rate In Google Analytics [analytics.blogspot.com]

Every click can also bring a searcher closer to a conclusion.

For example, when searching for a product you might visit the top site, find what you're looking for but then return to the results to see if anyone else sells it cheaper. Each subsequent click may confirm the top site offered the best deal so you spend less and less time on the lower placed sites and eventually return to the top one and place your order. If most people found the same thing the top site would remain top based on merit (user stats) - more time spent on site initially, plus visitor returned and placed an order.

However, most people might discover the best deal is on the 5th placed site, in which case the user stats would favour that site over time and eventually I would expect that site to rise to the top. User stats (Google's and each sites') indicate which site ultimately satisfied the searcher's query best, and the one that does the best job consistently will rise to the top and remain there (in my opinion).

The best site might not be the one that offers the best deal however. It may be the one that people trust most. Some people will go for price, some will go for trust, some will go for a balance of best price and a certain level of trust. It's the one most people lean towards that will eventually rank best though I think.

Google looks at the whole picture though, not just one statistic, but I do believe user stats are THE most important factor these days.