Wins across the National League and American League aren’t distributed equally. Looking at both current wins and our projected expected wins, the NL has more teams at the extreme ends of the wins spectrum, while the AL is more tightly grouped. The shape of the win distribution is useful because it can create a picture of the league. The AL has 20 more interleague wins than the NL due to the 140-120 AL-NL interleague record, so the AL’s distribution is shifted slightly higher than the NL’s. But the NL’s distribution is more spread out with more teams having either really good records or really poor records. Interestingly enough, one division, the National League Central, has the top three teams, Cardinals, Pirates and Cubs, in its league.
There isn’t too much difference between current and projected expected win box plots, but it’s scaled to a more familiar end-of-season win total.
These plots loosely imply there is more parity in the AL, but only in the sense that inequality is measured by single-season wins. Using the gini coefficient, an economic metric which was discussed at SaberSeminar during Bill Petti’s performance consistency presentation, we can measure the inequality within the two leagues and compare. The higher the gini coefficient the more inequality there is. The NL has a gini coefficient of 0.089 while the AL has less inequality with a 0.050 gini coefficient.
Finally, the Cubs, the projected second National League Wild Card team, are projected to have 94 wins, while the Angels (the American League counterpart) are projected to have 12 fewer wins.
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I think the line dividing light grey and dark grey is .500. What do the grey boxes represent?
One standard deviation? Error bars? Guessing.
Quartiles.
It’s the standard box plot. The middle division is the median, which falls around .500. The top of the box is the 75th percentile and the bottom of the box is the 25th percentile. The whiskers in this case are the minimum and max, but they won’t extend past 1.5 times the interquartile range: https://en.wikipedia.org/wiki/Interquartile_range.
Doesn’t this just tell us that the NL has 6 terrible teams and the AL has none?
Pretty much. PIT, SFG, ARI are the only teams with significantly above-.500 records against the AL. STL is 11-9, the only other team above .500 at all. Small sample size for each team, but that’s 4 out of 15. Which suggests that the gaudy records in the NL have been achieved by beating up on the bottom-feeders.
Or the IL record is inflated by mediocre AL teams beating up on the same bad NL teams.
About a week ago I was wondering the same thing about the top NL teams “beating up on the bottom feeders”. At that time the six worst records belonged to NL teams and the next six worst were AL teams and I lumped all 12 of them together in the “bottom feeders” category.
I found that the Cards did just slightly better against the bottom feeders compared how they did against the rest of MLB, the Jays did slightly *worse* against the bottom feeders, and the Royals did MUCH better against the bottom feeders. The Royals were only winning about 56% of their games against the non-bottom feeders, which brings them down to the Jays and Yankee’s level.
For this reason I think the Royals are highly overrated in just about everyone’s “power rankings”. And for that same reason I would love to see everyone’s standings include a “strength of schedule” number as in Hollinger’s NBA power rankings.
I tried to post my actual calculations in a comment on ESPN’s power rankings but I came out all jumbled because their comments page kept reloading while I was typing. I didn’t crunch numbers for any other teams because it is too much work when your only data source is things like the results listed for each teams schedule on TSN. Wish I could just download a CSV giving all results for the whole season.
Or 3 really good teams.
Why is the AL in the red? I always considered it the “blue league”?
http://lmgtfy.com/?q=interleague+play+logo