It is a stat that has been around for years. And it is so simple and logical that at first glance, it hardly seems worth mentioning.
And yet, run differential -- the gap between how many runs a team scores and how many it gives up -- has become more prominent than ever in recent years.
"I think in the last five years, it's really picked up," Bill Arnold of Sports Features Group said. "People are talking about it. Managers are talking about it. And I think that comes from the fact that baseball people themselves are looking at different ways to measure their team, or other teams', success."
Arnold notes that there are better "hidden" stats that measure the game. The idea that a team that scores more runs and allows fewer runs has a better chance of winning is, after all, slap-your-forehead obvious.
"It's one of those stats that's interesting to look at," Arnold added. "It creates a lot of talk about it. And teams use it to some degree. But to me, it's not a game-changing stat. It's just an interesting stat that's there, and it gives you a relatively quick way to look at what your team is doing."
Jacob Pomrenke, web content editor/producer for the Society for American Baseball Research (SABR), credits Michael Lewis' 2003 best-seller "Moneyball" with being a catalyst for bringing run differential and other sabermetric concepts into the mainstream.
|Athletics||+ 135||.625 / 1|
|Angels||+ 71||.586 / 2|
|Mariners||+ 64||.545 / 4T|
|Blue Jays||+ 26||.522 / 6|
|Tigers||+ 24||.565 / 3|
|Orioles||+ 23||.545 / 4T|
|Royals||+ 12||.517 / 7|
|Indians||- 13||.494 / 9|
|Rays||- 27||.451 / 11|
|White Sox||- 30||.472 / 10|
|Yankees||- 32||.506 / 8|
|Twins||- 35||.448 / 12|
|Red Sox||- 46||.443 / 13|
|Rangers||- 76||.432 / 14|
|Astros||- 87||.400 / 15|
"It's a relationship between runs scored, runs allowed and team wins that we've known about for about three decades now," Pomrenke said. "It was first discovered by Bill James and independently by Pete Palmer, two of the most prominent members of the sabermetric community in the late '70s and early '80s.
"Really, if you want to go back, these concepts have been around for more than 100 years. F.C. Lane was a great baseball writer in the early 20th century. Ernie Lanigan with The Sporting News. Those guys were coming up with these concepts. They might not have called them by the same names. They might not have explained them the same way. But the concepts were there."
So run differential is a handy way to explain what has happened. But can it be also used to foreshadow what will happen next?
"I'm a really strong believer in run differential being a logical determinant for a team's existing record and for its potential record, unless the team changes the elements that produce or prevent runs, such as adding a batter or a pitcher gets injured," GammonsDaily.com columnist Bill Chuck said. "I believe that in the long run, logic wins out as a litmus test in how well a theory stands up."
"You can use it to predict future performance in a general sense," Pomrenke added. "It's not something you can really take to the bank as exactly what's going to happen. Baseball is a funny game, and there's always some 'X' factor in there that can change things up ... You would expect that over the course of a very long season, that teams are going to regress one way or the other to what their true talent level is."
|Dodgers||+ 62||.560 / 2|
|Nationals||+ 59||.552 / 5|
|Brewers||+ 31||.584 / 1|
|Giants||+ 28||.557 / 3T|
|Cardinals||+ 16||.528 / 7|
|Reds||+ 15||.517 / 8|
|Braves||+ 12||.557 / 3T|
|Marlins||+ 4||.489 / 9|
|Pirates||- 1||.534 / 6|
|Mets||- 3||.443 / 10T|
|Cubs||- 13||.442 / 12|
|Rockies||- 40||.416 / 14|
|Padres||- 51||.443 / 10T|
|Phillies||- 56||.420 / 13|
|D-backs||- 72||.411 / 15|
The general idea here is that teams will eventually end up where they're supposed to based on how good they are. So if its run differential is wildly out of whack with its record, it could be a sign that an adjustment is coming.
That's not always the case, of course. The 2012 Orioles are a good example. Baltimore scored just seven more runs than it allowed that season. Its Pythagorean record, according to an equation developed by James and based on run differential, should have been 82-80. Instead, the O's won 93 games. The reason: They were a remarkable 29-9 in games decided by one run.
It can be analytical. The Giants fell on hard times just about the time outfielder Angel Pagan went on the disabled list. That could be interpreted as an indication of Pagan's importance to the team, both offensively and defensively.
It can also reveal fascinating nuggets. Last month, the Padres were minus-35 despite decent pitching. But San Diego scored just 60 runs in June.
Sometimes a streak of luck, good or bad, can impact the run differential. Again, the supposition is that over time, that will even out. So what does it mean that:
The Pirates are 47-41 despite a minus-1 run differential?
The Nationals (plus-59) are only a half-game behind the Braves (plus-12) despite a much better run differential?
The Yankees are one game over .500 despite being minus-32?
Several contenders were outscored in June: Giants (minus-23), Braves (minus-7), Blue Jays (minus-5), Cardinals (minus-3) and Tigers (minus-1)?
It will be fun to watch and find out.
Paul Hagen is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.