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Sabermetricians haven't even begun to touch the question of, "what makes a particular player have a good year?," much less what makes a group of them have a good year together.
Staffs of pitchers, at certain times in certain places, have had good years together -- pitching under Sain, or Mazzone, or what have you.
If Dr. Elliot's training system *did* cause the Mariners' kids to have a good year together, it would be invisible to sabermetrics both before and after the fact. That wouldn't mean it hadn't been real, and causative.