I'm not sure this tool makes any intuitive sense, and there's no way Grady Little would use this... But it looks kinda interesting: http://www.visual-io.com/baseball/
The tough part is that you can never go back and compare what the results would have been if you had made a different decision. So you'll never be able to test whether the Manager's gut feeling or the tool's suggestion is a better choice, will you?
(Thanks to marc for the link. And now marc, I'm getting to work.)