The player dialogs all work the same, in that only the currently visible and checked players are acted upon. So if you have your entire database of players listed, check everyone, then search for "a" and the search results in only one player listed, then press OK only that one player will be acted on (bought-in, rebought, whatever is happening).
While this certainly does not count as a complete sample, all of the feedback on this thus far has been negative, so I think I'll have to return it to the previous behavior. Or I'll add a preference to toggle it.