How do we project players?
Most of you know about projection systems like PECOTA, ZiPS, CHONE, or Marcel that attempt to predict how a player will perform in the future. If you're a fantasy junkie or a rosterbator, that stuff is a must. If you like hanging out at AN and discussing who to sign, who to trade, and who to DFA into oblivion, having projections around can be helpful.
Projections typically rely on mathematical formulations, and while each projection system is different, most of them have the same inner workings:
- compile stats from the past few years, weighting the most recent stats most heavily.
- regress to the mean.
Projections systems differ in the details: which stats they use as for inputs, how the weights are assigned, whether league and park adjustments are made, which mean they regress toward, etc.
There's a second critical bit about projecting player performances: our eyes. Objective information, even if it is not quantified, can help us make determinations about players. The classic example is injuries. Tim Hudson is projected to have a 4.06 ERA in 150 IP by Marcel, but Marcel doesn't know that Huddy just had Tommy John surgery on his throwing elbow. Sometimes pitchers add a new pitch. Sometimes batters change their mechanics. Sometimes these things can change a player's performance level, and sometimes they don't. It is worth at least thinking about what non-statistical objective information is useful.
That's why I think The Hardball Times 2009 Season Preview is a great book. In addition to over 1000 player projections and all 30 team projections, you get awesome commentary on players and teams. The projections are done by smart analysts. The commentary is written by fans who live and die with their team's every pitch. Jeff Sullivan wrote the Mariners chapter. Justin Inaz wrote about the Reds. It's like an all-star roster of bloggers and fans.
Oh yeah, I wrote the A's chapter.
Here's what the book's editor, David Gassko, has to say:
This is the third year we’ve done this book, and it’s the third year that I can honestly say we’ve surpassed my every expectation. I know my opinion is biased, but our writers have done a fantastic job covering every aspect of the upcoming season.
The projections include all the regular statistics you might expect, plus fielding ratings, three-year projections, a reliability score, projected fantasy values, and depth charts. In other words, no matter what you’re using these projections for, we have you covered.
The book also includes a review of 100 players by an injury expert, commentary on rookies to watch for, and - for the fantasy players - an essay on managing risk in your fantasy draft. Purchasers receive not only the book, but access to a spreadsheet with over 2600 projections.
So I come to you, hat in hand, asking you to consider purchasing what I consider to be the essential pre-season guide to the 2009 baseball season. Your purchase supports THT, which - in my opinion - is the best free baseball site on the internet.
If you do want to buy the book, consider purchasing it directly from ACTA instead of from Amazon. If you purchase it from Amazon, the six bucks you save comes directly out of THT's cut. If you do purchase from amazon, consider donating part of your savings back to THT from the PayPal link at the bottom right of our homepage.
And if you've made it this far, I'll give you a sneak peak at some Oakland projections for next year:
Devine: 3.08 ERA
Duke: 3.82 ERA
Ziegler: 4.41 ERA
Gallagher: 4.49 ERA
Cust: .893 OPS
Giambi: .875 OPS
Barton: .737 OPS
Crosby: .635 OPS