Here at FanGraphs, we’re big fans of Sean Smith’s CHONE projection system. It’s proven to be equally or more accurate than any other projection system out there, he provides the data for free on his site, and he’s a good guy.
So, today, with news from the game at a virtual standstill, I figured we should take a look at the projected standings that he recently put up, based on the CHONE forecasts and his playing time estimates.
None of the projections should be all that surprising. The East divisions are very good, the West divisions are not, and the AL is still better than the NL. Perhaps fans in LA will be surprised by the lack of wins projected for their two teams, but as we’ve talked about, the Angels win total was built on a house of cards last year, and the Dodgers haven’t re-signed Manny Ramirez yet.
I know that whenever a projection system is published, a bunch of you guys immediately look at the results and proclaim they’re too low, because the projected leaders have less wins/home runs/strikeouts/whatever than the previous historical leaders. As we always try to explain, that’s because of regression to the mean. We understand that the final AL West winner isn’t likely to have 85 wins. Even CHONE will agree with you on that.
Let’s walk through an example, shall we? The Angels are projected to win the AL West with an 85-77 record. But that’s just a mean projection, based on the range of probabilities of the Angels winning anywhere between 60 and 110 games. Obviously, at the extremes, the odds are very tiny, so the distribution of the probabilities will look like a bell curve. Actually, let’s just show it to you.
At each win total between 81 and 89, there’s a greater than 5% chance of that win total occurring, if we agree that the Angels are a true talent 85 win team. There’s less than a 1% chance of each win total at less than 72 or greater than 98, but those are still possibilities, even if they’re pretty unlikely. Those are the individual probabilities – now let’s look at the cumulative probability.
We find 76 wins at the 90% mark. In other words, we’d expect this Angels team to win at least 76 games 90% of the time. 50% gets you to 85 wins, while 10% gets you to 93 wins. So, while 85 wins is the mean for the Angels, and they have the highest mean of any team in the division, it is not predicting that the division winner will finish with 85 wins.
The Angels have a 19.3% chance of winning 90+ games, based on this distribution. But they’re not the only team in the division. The A’s, with their projected 81-81 record, have a 6.7% chance of winning 90+ games in 2009. The Mariners, with their 78-84 projected record, have a 2.4% chance of winning 90+ games. And the Rangers, projected at 72-90, have a .1% chance of winning 90+ games. The sum of these probabilities is 28.5%. In other words, despite projecting the best team in the division to win 85 games, CHONE is still saying that there’s a 28.5% chance that the division winner will win 90+ games.
Hopefully, this is somewhat helpful – when you look at projected standings, they are giving you relative strength from team to team. In every division, it’s pretty likely that some team will outperform their expected win total, and that the division winner will end up with more wins than the mean of the projected top team. This is not a flaw of projection systems – it is a reality of math.
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