Archive for December, 2015

The Beginner’s Guide To Aging Curves

This time of year is about roster decisions. Teams are working to build their 2016 rosters with an eye on how 2016 fits into their overall plan. Some teams are looking at their current roster and payroll and deciding to go for it, while others are setting themselves up for a bright future. Clubs are making trades and signing free agents, and from the outside, we’re trying to figure out which moves are good and which aren’t.

There are a lot of factors that go into evaluating a particular transaction or set of transactions. Far too many to talk about all at once. But we can generally agree that our attempt to forecast future player performance is central to any effort. In order to know if the Cubs made a smart move in signing Ben Zobrist, we need to develop some prediction about how good Zobrist will be over the life of his four-year deal. Obviously, this is a tricky business.

We are trying to project Zobrist’s future. We’ve talked about projections in this space before. They are estimates of true talent, adjusted for aging. You can read more about the basics here, but this article will focus on the aging component. In order to make decisions about players, we need to know how good they are presently and how those skills will improve or decline in the future.

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