I hate when great players become managers. It almost never works out. Think of Ted Williams and the Washington Senators...It worked out so horribly that the Splinter was named Manager of the Year in the American League for 1969.
Williams only had problems in the last couple of years the Senators were in Washington, when owner Bob Short was pretty much turning the club topsy-turvy with insane deals and moves the better, perhaps, to hype his hankering to get the hell out no matter what he was saying publicly.
I can name you a few other great players who became serviceable managers, at least. Gil Hodges, for one. Bill Terry, for another. Yogi Berra was a good manager whose organisations (the 1964 Yankees especially, and shamefully) undermined him when all was said and done. Lou Piniella was an excellent player and became a World Series-winning manager.
The word out of the Cubs organisation (ok, ok, I know) is that Ryne Sandberg, a Hall of Fame player, is proving an excellent manager in their system who just might get to manage the Cubs or elsewhere in the Show in the future. And it's easy to forget that Joe Torre as a player alone is a borderline Hall of Famer; as a player and manager he just might make it after all on a combine entry. Red Schoendienst proved a Hall of Fame player and went on to become a World Series-winning manager. Hall of Famer Frank Robinson was a fine manager who probably deserved better when he did manage. Bob Lemon was a Hall of Fame pitcher and a good manager (he won a World Series managing the Yankees) who likewise deserved better as a manager. (Come to think of it, how many pitchers, period, never mind Hall of Fame pitchers, make useful, never mind winning or great managers?)
What about this one: http://losangeles.angels.mlb.com/team/coach_staff_bio.jsp?c_id=ana&coachorstaffid=121919