I'm not particularly interested in MadBum (at least if you give up much value for him), but part of the argument in trading at least SOME of these arms now is that their value likely has nowhere to go but down. AA and his guys aren't fortune tellers either, but I hope they're much better evaluators than anyone here. While Bumgarner may not be a great example of someone to target, there are several other players out there worth overpaying for - some of whom are TOR type arms.
The value charts are TOOLS - great tools for small- and mid-market teams - but still only tools. For all the numbers can tell you, they're simply not a guarantee of anything. They should be consulted as a guide, with the decision-makers also exercising some level of "educated guessing" based on other factors. Is a TOR starter an absolute necessity when it comes to winning the World Series? Obviously not. However, do you honestly think ANYBODY associated with the Red Sox in any way (Manager/Coaches, players, front office personnel, or fans) gives two *hits about whether someone is still beating the drum about the fact that they "overpaid" for Chris Sale, or that they have a chart that clearly shows they did?
The charts are great (and no one will argue that they're right the vast majority of the time), but they show you things that assume ALL these prospects will stay healthy AND reach the ceilings they project. Common sense tells you that that's simply not going to happen. If you're in AA's position, you talk with the numbers guys to develop "your list" - the players who COULD be the best ones if everything works out. You then go to your scouts, Coaches, and player development people with that list and say "we're keeping X number of guys on this list - give me the ones you'd keep in order" AND the reasons why and you go from there.
Does anyone honestly think anybody in Boston would be interested if the White Sox called and said "hey, we'll give you back all the guys you sent us - plus a couple B prospects - if we can have Sale back"?
The folks that came up with much of the "new math" are extremely intelligent people, but they wouldn't either today. The constantly referred to "smartest" organizations in baseball (Tampa Bay, Houston, the Dodgers, etc.) definitely have something in common - they'll be watching the parade in Boston tomorrow on TV with the rest of us.