Mabry is a very significant upgrade from Macias, no question. He's not a good hitter by any standard, but he's a better hitter than Macias. His eqa was .244 last year, but Macias' was a stunning .210.
The numbers are correlation and root mean square error against runs scored. That seems pretty marginal to me. On-base plus slugging .922 25.54
Equivalent Average .928 24.13
BaseRuns .930 24.38
eXtrapolated Runs (per PA) .920 24.83
Runs Created (per PA) .928 24.96
Total Average .926 25.33
As bad as you make it out, OPS correlates pretty well with runscoring. I don't really think you can go wrong with it. The more advanced stats might give you a clearer picture, but they probably won't ever tell you anything dramatically different.