In a recent posting, I argued that OPS [On-base-percentage Plus Slugging-average] is an excellent comparatively easy and comparatively good statistic to use for assessing the performance of batters in baseball.
For the same reasons, I think OOPS [Opponents' OPS] is a comparatively easy and comparatively good statistic for assessing baseball pitchers. The statistic is readily available via the MLB website, and it measures how well a pitcher avoids letting batters reach base and how well the pitcher avoids letting opposing batters hit for power.
I have noticed that baseball sportscasters are moving toward telling us about opponents' batting average [which tell us nothing about walks given up nor about extra-base hits] or about WHIP, which is Walks plus Hits per Inning Pitched [which is a bizarre measure telling us nothing more than (and really not as much as ) "Opponents' On-Base-Percentage].
Maybe in another ten years' time they will start using OOPS as well as OPS.
May I live to see the day.