This is not exactly an original idea. It has been addressed before by Stacey Long over at Camden Chat. They decided to use the Orioles' winning percentage in each division to determine how the team would perform with various unbalanced schedules. In that article, Long found that the Orioles' record in 2009 would have improved by four games had they played in an easier division. I think that is solid work, but I wonder if the number of games the Orioles play against other teams in the other divisions is robust enough. Daniel Moroz of Camden Crazies wrote over at Beyond the Box Score a short piece trying to determine what the difference playing between divisions would be. Moroz used an elegantly simple set of assumptions (e.g., typical wins by AL East teams, an 81 win average for AL teams, interleague play winning percentages) along with Bill James' log5 calculations. He found that unbalanced schedules could cause changes of a win. That is not much to be concerned about. So, two solid articles with two different conclusions.
This well tread idea needs, perhaps, another way to address it. I propose that WAR (Wins Above Replacement) could be used to determine how many games a team could win by shifting divisions. You may have noted in the past that if you sum up all of the WAR of individuals on a single team, you wind up with a number that is anywhere from 35-55 wins less than the actual total wins that the ball club earned. This makes sense as a replacement level team (roughly defined as a team composed of AAA players) would be able to win a game here or there. WAR actually relates rather well to actual wins. The graph below illustrates how WAR relates to actual wins for AL teams from 2002 to 2010.
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The trend line shows a good fit between wins and WAR with an R-squared of 0.81. The y-intercept (where the line crosses the y axis (the vertical one)) is the number of wins that would be expected to be won by a replacement level team. As this can be done with all of these data points from 2002 to 2010, we can also do something similar for teams in each division for each year. With fewer data points, the correlation will not be as strong, but using replacement level performance as a base line for each division would provide a different way to measure how a team would perform in a different division. The following graph illustrates Replacement Level Wins (essentially Average Wins minus Average WAR) for each division.
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The graph above passes a general smell test for me. My perception has been that the AL East is the toughest division to play in because there is a concentration of talent of both young players (Tampa Bay Rays) and free agents (New York Yankees). It has also been my perception that this concentration of talent has been challenged at times, which is also indicated in the graph above. What I find interesting is that over this stretch of time, a replacement level team shifting from the AL East to the AL Central or AL West would improve by one and three wins, respectively. If you translate that into free agent money (4.5 MM for every win), you could say that it costs 4.5 MM less to compete in the AL Central or 13.5 MM less to compete in the AL West.
Again assuming that the replacement level is additive, we can determine how well the Orioles would perform in "weakest" AL Division each year over the past nine years.
Comparing our results to what Long and Moroz found, we see in general that our numbers fit in more with Long's in the idea that shifting divisions would cause a decent sized shift in the number of wins. When we specifically unravel Long's predictions for the Orioles in the AL Central from 2002 to 2009, we do not see a strong match between our efforts. Years in which I show little difference between the AL East and AL Central (e.g. 2005), she shows a difference. In my opinion, I think this is largely a product of there may not being enough games played when using one team's winning percentages to determine division strength. What is certainly known by all of these efforts is that simply moving the Orioles to another AL division is not a cure for what ails them.
In the near future, I will be using this approach to address the addition of a fifth team in each league's playoffs and will try to determine how good that team would be in comparison to the current field.