Predicting baseball is really, really hard. Very hard. There are thousands of different variables to consider, and even when you've considered all of them, sometimes a player will do something completely different just to mess you up.
Projection systems are a way to try and remove all of the emotion out of predicting, instead focusing on cold, hard numbers. They try to correct for outliers and focus on smoothing out the effect of luck, both good and bad. Ultimately, projection systems as a whole are reasonably accurate and a great way to evaluate players.
And yet. Sometimes, projection systems miss so, so hard.
The Kansas City Royals climbed to 77 wins, a total that eclipsed Baseball Prospectus' PECOTA projections for the Royals this year as PECOTA had the Royals winning only 76 games. If this sounds like routine to you, then you'd be right. It is the seventh consecutive season that the Royals have outpaced the PECOTA projection for wins. Here's a look at the year, projection total, real life win total, and difference:
|PECOTA win projection
|Actual win count
A few of those earlier projections were pretty close. All in all, a miss by one or two wins is actually pretty accurate. But something in the PECOTA projections seems broken, at least for these Royals--not only has the team consistently performed better than PECOTA predicted in both good and bad years, but recently the problem has been excacerbated. From 2013 to 2015, the Royals won a combined 43 more games than PECOTA predicted they would. And as the Royals got better, the projection system didn't keep pace.
Even if the Royals lose the rest of their games this year, they'll still outpace their PECOTA prediction yet again, but the Royals have an opportunity to destroy PECOTA, too. If the Royals win nine of their last 12 games, they'll end up with 86 wins and will have beaten the PECOTA projections by at least 10 wins for four consecutive seasons.
Say what you want about the projection systems, but the more these Royals teams win the more it looks like the projection system is missing a core reason why Kansas City has had such a great run. At the very least, hopefully the Royals will be able to help projection systems get better, which is a great goal. That we have a few flags to fly for our trouble is pretty nice, too.