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A Look At The 2016 Cubs' Run Differential

An updated look at the Cubs run differential and projected winning percentage. At +194, they are well on their way to a historic season in 2016.

It's all smiles in Chicago right now. With Jorge Soler back, the Cubs run differential gap continues to widen.
It's all smiles in Chicago right now. With Jorge Soler back, the Cubs run differential gap continues to widen.
Caylor Arnold-USA TODAY Sports

EDITOR'S NOTE: Please welcome Jordan Kloewer to the front page of BCB. He'll be writing about the Cubs from a statistical/sabermetric viewpoint.


Since I first wrote an article on July 28 regarding the Chicago Cubs historic start to the season and the lull that followed, things have changed a little bit. The Cubs are 13-3 in their last 16 games including sweeps over the Marlins, Athletics, and Angels. They've won three games in dramatic walk off fashion, and everything again seems right in Wrigleyville.

Run Differential

I'll start out today by focusing on the Cubs' run differential (Runs Scored - Runs Allowed). After an historic start, they reached their pinnacle after the 67th game of the year against the Pirates. At this point, the Cubs were 47-20 and had outscored opponents by 171 runs! After that game, though, the ball club went 13-20 and their Run Differential dropped 18 runs to +153. In the past 16 contests, the Cubs have outscored their opponents 83 to 42 and have increased their run differential to +194 which is close to the new maximum point on the year (+200 after Friday's win).

The Cubs +194 mark is 52 runs better than the next closest team (Nationals). The Cubs and Nationals are the only clubs to have a run differential that is greater than +105. The second place Cardinals were ranked third in the league at +95 on July 28 but have fallen dramatically in the past 19 days. They are now at +64 on the season (-31 during the same stretch that the Cubs were +41). While the Cubs dominate the top end of the spectrum, the Braves, Diamondbacks, and Reds all have a run differential worse than -100 in 2016. The Reds have a -122 mark, largely due to the thrashings they have taken at the hands of the Cubs so far this year (they're -55 against the Cubs alone). The Braves have the worst differential at -136 runs. The Cubs offense has scored the third-most runs in MLB, while their pitching staff has allowed the fewest runs in baseball.


Projected Runs to Wins

In a previous article of mine, I introduced the "Pythagorean Theorems of Baseball" which basically tries to determine the number of games a team will win based on their number of runs scored and number of runs allowed. Here are the formulas again for six of the most common win percentage projection formulas:

I added up the Cubs total runs scored and total runs allowed after each game this year and compared their actual number of wins to the projected number of wins based on each formula. These charts visualize the differences between those numbers.









This matrix summarizes how accurate each of the projection formulas has been in predicting the Cubs winning percentage and total number of wins so far in 2016. The most accurate formulas was the James_1.83 followed by the James_2 and Soolman. Four of the six formulas were very good predictors, but the Cook and Kross formulas overforecasted the number of wins that they expected the Cubs to have. Notice that at one point this year, each of those formulas projected the Cubs to have over 15 more wins than they actually had. The R^2 value (coefficient of determination) is indicative of how well the projected win percentage matched up to the actual win percentage after each game this season.

All in all, the Cubs have should have at least five more wins this year based on these formulas. Scoring as many runs as they have (third most in MLB) and allowing as few runs as they have (first in MLB) should result in an even better record than 73-43. The Cubs are putting up record numbers in the run differential category, and they have continued to add to their impressive marks during the past 16 games. We will see if these numbers continue on an upward trend as the "league outlier" or if they start to flatten out back closer to the league mean.