What is the value of upgrading starting pitching?

We all know what the rough cost to acquire an ace pitcher like David Price, Jon Lester, or Cole Hamels would be. We’ve seen that discussed by the media over and over again over the last couple months. But what we don’t know is really what the net effect would be to the team. Well, I attempt to answer that.

Of course there isn’t a way to tell the future. Any of those three pitchers could put together an incredible final two months of the season or the offense could provide him an incredible amount of run support. Those are all variables that have a great effect on these calculations. For the sake of discussion, we’ll assume that all pitchers will continue pitching to their current season averages for the remainder of the season.

The first step was to determine how many runs per inning each pitcher allowed and then how many innings per start they went. Multiply that and you have the runs per start allowed by the starting pitcher.

You can then take that and figure out how many innings the bullpen needs to cover and do the same math for them to figure out how many runs they’ll allow in the remaining innings. Add it with the starter’s runs per start and you have the number of runs allowed per game.

Then you take the offense’s average runs per game and then you can compute via the pythagorean expectation the expected winning percentage given those numbers. And get the record.

So here’s what the expected records for the Cardinals in each of the final 12 starts of the season for each pitcher, given the Cardinals’ offense and each pitcher’s performance so far this season,

Shelby Miller, 5-7
David Price, 6-6
Jon Lester, 8-4
Cole Hamels, 8-4

Is three extra wins worth the cost of acquiring a Lester or a Hamels? Or one extra win worth the cost of acquiring Price? The Cardinals are 2.5 games out of the division lead right now. They are expected to go 88-74. Those three extra wins might be worthwhile.

Is there a deeper way to do this? Yeah. And I’m sure the Cardinals have done something much deeper internally. This is simply a really high level look and the potential effect of acquiring one of these pitchers. There’s really only a maximum of 12 starts available for any acquired starting pitcher, so their impact in the regular season is really going to be small, really not going to be more than a couple wins. I mean, the Cardinals are 4-8 in Miller’s last 12 starts and he has a 4.80 ERA, even worse than used in these calculations.

But their value would be made in the postseason, where an established top level arm may provide better odds of winning.

Which was really my argument for the Cardinals acquiring a pitcher like Price, Lester or Hamels. The overall regular season effect at this point is small, you don’t make the trade for the regular season. You make such a move with an eye on the postseason. I believe our current rotation’s worth of arms can get us there, but I don’t think they can get us through October.

If you’re interested in looking at my math. It was really simple.