The Importance of Run Differentials

Before we get to today's geek stuff, let's give a shoutout to the Bulls and DBAP crew that managed to host more than 30,000 fans this weekend. Very well done. Thank you! Let's not forget just how great the Bulls looked in the first two games of the Scranton/Wilkes-Barre RailRiders series. Let's try to look past the 13 (count'em, 13!) baserunners stranded in the last game.

About Run Differentials

This is a very simple statistic, the number of runs scored minus the number of runs allowed. But it's right up there with won-loss in importance. There's even a variant stat based on run differentials called Pythagorean Expectation, which we won't go into today, but is a lot of fun to track.

This first chart shows the cumulative game-by-game run differentials so far this year. As of today the Bulls have scored 402 runs and have allowed 330 for a run differential of 72, down slightly from Saturday's peak 0f 76. Nevertheless, pretty darn good at game 69 (they are just one game from mid-season).

Why Do They Matter

Look at the last several years. During those years the Bulls won four Governors' Cups (2011, 2013, 2017, and 2018) and won the IL South. Take a look at the run differentials for those years. All of them were positive — for the G'cup years, they were exceptional. Note: The Bulls also won the IL South in 2008, 9, and 10 with positive run differentials, but this chart was already cluttered enough.

Which brings me back to today. The Durham Bulls at midseason are looking very, very good. Their numbers are up there with those from 2017 and 2013, great years for Bulls (and Bulls' fans).

RailRiders Come to Durham

The Scranton/Wilkes-Barre RailRiders come to town today. They are the New York Yankee's AAA team and the buzz is that rehabbing Yankee's stars Giancarlo Stanton and Aaron Judge could join the team in Durham.

But for a Bulls fan, the better story is that the two best teams in the International League are meeting for a 3-game matchup to be followed by a visit to the RailRiders' home field next week.

The Bulls are on a 6-game winning streak and have won 8 of their last 10. The RailRiders had a recent streak broken, but they have won 7 of their last 10. The Bulls are 3½ games up in the South, the RailRiders are 5½ games up in the North Division.

These are very well-matched teams and, with any luck, we could be seeing some of the most interesting baseball of the year this weekend and next week (assuming you've got MiLB TV).

Ugly Home Stand, So Far

This home stand is not going well. So far the Bulls have lost 5 games and won just two. Two key players were called up (congrats to Nate Lowe and Christian Arroyo) and catcher Nick Ciuffo, who was really improving at the plate, got hurt. Otherwise, it's a bit hard to peg just one reason.

Yes, the Bulls got shut out for just the second time this season. Yes, in one game they gave up 3 unearned runs. But the team ERA is virtually unchanged as is the team batting average. About the only metric that I watch that's been a problem is the opponents' Secondary Average. And that's grown quite a bit, reflecting on the 14 (count 'em, 14!) home runs hit by Louisville and Columbus. The Bulls hit 7 in the same period. Maybe that's what's made the difference.

At any rate, the Durham Bulls are out of first place in the South, with three more home games (against Norfolk) to go.