Among saberists, the opinion of Ryan Howard's new 5 year, $125 million contract extension seems to be fairly universal. That being, basically, he's not good enough to justify the money, he's too old to justify the years, and his body, swing, and playing style are all likely to age poorly. Exactly what does this mean, though? Or, how badly did the Phillies get burned?
I used the slash line ZiPS projections Dan Szymborski published here in conjunction with the regression equation Adam Dorhauer published here to estimate Ryan Howard's weighted on base average going forward. With this, we've got something we can easily convert into run values, given his playing time. You know the drill from here. Add in fielding (bonus: use the UZR aging curve Jeff Zimmerman published here), positional adjustment, and replacement, and divide by the league's run-to-win conversion factor. And we've got Howard's projected win values--the basic commodity of baseball economics.
For the sake of generosity, let's assume Ryan Howard stays extraordinarily healthy for the life of his contract and accumulates 700 PA's, something he's actually done thrice, each year through 2017. By being generous with the playing time projections, we're being inherently optimistic about Howard's overall value. That's OK, what we're looking for is a sort of "best case" scenario. Here are the results:

And so with these projections in mind, how does the deal look for the Phillies?

It's easy to see why the sabermetric community has reacted so negatively. If ZiPS is even close to right--even if Howard stays unprecedentedly healthy--this deal isn't going to look good. Of course, nothing is out of the question, and we don't know this deal will end badly. But right now, that's where the smart money is.