FG on Fox: The Over and Under Achievers

There are six weeks left in the 2014 regular season, and if the season ended today, we’d have some fairly surprising playoff teams. The Brewers are in first place in the NL Central, the Orioles have a huge lead in the AL East, and the Mariners are tied with the Tigers for the second Wild Card spot. You probably didn’t predict any of those outcomes, and I know I certainly didn’t. This is part of what is great about baseball, and especially in the current age of parity, the playoff teams are no longer as predetermined as they once seemed.

Results like these often convince people that preseason forecasts are basically useless. As you’ve probably been told repeatedly by various announcers and baseball scribes, the game is played on the field, not on a spreadsheet. However, I thought it would be instructive to look back at the forecasted performance from the beginning of the season and see how well they managed to evaluate expected performance.

To do this, however, we’re not going to compare the projected standings to the actual standings, because a team’s record is essentially a function of two things: how many hits, walks, and other positive events a team creates relative to how many they give up, and the timing of when those events occur. The first one is what projection systems specialize in forecasting, but they really have no way of knowing which teams will tend to bunch their hits together, or distribute their runs in such a way as to win a bunch of close contests.

The timing aspects of win-loss record is basically random, and since there’s no real way to project it in advance, we don’t really want to judge how well a projection did based on results that are influenced by randomness. Instead, we’re better off looking at just the quantity and value of the types of baserunners a team achieved over and above what they gave up, and evaluate the preseason forecasts based on how well they match up with what a team’s expected record would be without the timing effects that can skew runs and wins. After all, that is really what the forecasts are trying to measure.

At FanGraphs, we publish the seasonal data from a model called BaseRuns, which takes all of the events a team creates and allows and turns them into an expected runs scored and runs allowed total. Based on those numbers, we can come up with an expected winning percentage that doesn’t factor the timing of events into the results, and so that’s what we’ll use to measure the team forecasts.

Here are the top five teams that have outperformed their preseason expected winning percentages.

Read the rest at Just a Bit Outside.