Fair attitude in general to have, longing for simpler times. That said, if the Brewers did not think outside the box like this they'd have no chance. Because the obvious things you point out that every player/team should want, welp everyone knows that and those guys get the big bucks. Which MKE can't do. Thus, they have to scrap together an edge where they can. And I'd by no means call them useless, its how teams like MKE, Cle, TB and OAK (before they intentionally quit) keep winning. And a really simple way to look at some of it is that one run taken away from the other team is just as useful as one run scored for your own, that's the 'efficiency' that MKE has figured out because elite D and relief pitching does not cost near as much money as the obvious stats that you pointed.
But mostly I was just gonna say don't get too caught up with the "Wins" aspect of WAR, its a bad or deceptive name. Just view it as a metric for average/mediocre that is trying its best to aggregate all metrics. Think other sports use similar things Player Efficiency Rating and things of the like or think of QB rating in football. This name implies too much direct correlation to Win.