In this piece, we talked about how the PECOTA projection system has undershot the number of Angels wins by an average of eight games since the 2004 season. But why?
Colin Wyers of Baseball Prospectus had a few thoughts on the matter and passed them along to Mark Simon in the ESPN Stats and Info department. The crux is that the Angels outscore their "run differential" in a typical season through good base running and above-average outfield play. In this regard, Simon and manager Mike Scioscia are in full agreement. As Scioscia points out, there's more to scoring runs than just getting to first base.
Basically, people looking to project a team's winning percentage look at their runs squared divided by their runs squared plus their runs allowed squared, Simon explains.
If you do that last year, you get 681 runs scored times 681 = 463,761. Divide that by 463,761 plus [702 runs allowed times 702] = 492,804 divided by 956,565 and you get a .484 winning percentage. The Angels' winning percentage was .494 last year. Pretty close, right?
But in the previous four seasons, the Angels won as many as 12 and no fewer than four games more than this projection system would have estimated.
Conclusion: The Angels didn't run the bases or play the outfield as well as in previous seasons. Sometimes, numbers tell us exactly the same thing as our eyes.