"Further using your example, walking Barry Bonds with the bases loaded was never a good decision. Ever. There was never a point in Barry Bonds' career when the chance of him driving in more than one run without recording an out was 100%, so giving him a 100% chance of reaching base and the Giants scoring a run was a bad decision."
JH,
There doesn't have to be anywhere near 100% chance of Bonds driving in more than one run for this to make sense. If I'm up by 2 or more runs, I may well be better off taking 100% chance of the Giants scoring 1 run by walking Bonds, rather than pitching to him and taking xx% chance of the Giants scoring 2 or more runs and tying or winning the game. If "xx%" is 90% this is certainly true, and probably true at 50%. I don't know how low this percentage would have to be to pitch to him, but that's the manager's call.
Actually, this is an intriguing response. Smitty- correct me if I'm wrong, but I think this has to do with the economic theory of marginal propensity to consume…in this case- accepting the present value of something in return for the future potential results. I think that this particular scenario might prove difficult to quantify the true value of the decision-making process, but in theory, I don't think you're wrong.