This isn't immediately relevant to anything we've been discussing today, but I found it this morning while searching for something else and thought I'd share it. Here is the full list of position players in their age 38 or older season who have made a positive rWAR contribution to a team in 2011:
That's all of them. There's only six, and just one of them that's been worth more than one win. That player, by the way, may need knee surgery.
If you add in players in their age 37 season you get a total of 14 players, with just two above one win (Todd Helton is the other). Adding in the 36's only gives you four more players, with Orlando Cabrera as the best one (0.5 WAR for the Indians).
I don't mean for this to be a commentary on the Braun deal specifically but I think it pretty clearly shows the risk involved in locking a player, any player, up for the decline years in his career. Across baseball there simply aren't many players right now remaining productive into their late 30's, much less their early 40's.