By Robert O’Connell When Brittney Griner was detained, it was—among many other, far bigger concerns—a wrench in the plan of the Mercury, which, with the addition of the underrated Charles, expected to be a title contender again this season. Before a mid-May practice at the Mercury’s facility in Scottsdale, Ariz., Tina Charles worked through her offensive repertoire. Or, rather, she worked through what portion of it she could, in the space of a half hour. Charles possesses her sport’s thickest catalog of low-post maneuvers: pivots and reverse-pivots, shoulder-shimmy misdirects, up-and-unders an…