There were only nine games on Thursday's major league schedule but we saw enough baseball for 11. That's because the A's needed 18 innings to beat the Yankees in Oakland, the Cubs took 14 to outlast the Reds and the Orioles had to play 13 to edge the Red Sox.
If it seems like there are more extra-inning games than usual this season, it's because there are. There have been 110 extra-inning games thus far in the 2013 regular season. If things continue at that pace, this season will shatter the previous mark for extra inning games set just two years ago in 2011. There were 237 extra-inning games that year. This year, we're on pace for 272.
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Yestersday's 18-inning contest in Oakland was the fourth game to go at least that far this season, the second in Oakland and the third in June, which is not yet half over. Last Saturday saw two games go 18 innings for just the second time in major league history, and one of them -- the Mets and Marlins -- needed 20 innings to settle things.
Why has there been so much bonus baseball? A couple of reasons are obvious. To begin with, there are just more games now in the expansion era: 2,430 games in a modern major league season compared to the mere 1,232 per season back when there were just 16 teams and a 154-game schedule.
Second, scoring levels are lower this year than they have been at any point since the last round of expansion in 1998. There have been just 4.25 runs scored per team per game thus far this season. That's down from 4.32 last year and 5.14 at the juiced-era's peak in 2000. Generally speaking, the lower the scoring levels, the greater chance a game will remain tied after nine innings, in part because there's a narrower range of score probabilities, and in part because teams have a harder time scoring to break those ties (which is particularly evident in those marathon games).
That said, scoring levels haven't taken such an extreme dip that that alone would explain why this season is on pace to break the single-season record for extra-inning games by almost 15 percent this season. Truth be told, it's more likely a fluke than anything else, and with 60 percent of the season left to be played, that spike could flatten out as we get into the warmer months in which scoring tends to increase.
Still, there really have been an unusual number of extra-inning games this year. As ESPN's Jayson Stark noted on Twitter yesterday, this is the first month with three 18-inning games since May 1973 and just the fourth ever, adding June 1967 and August 1972 to that list. Note that those other three seasons clump up in the last great pitching era in major league history. There were just 4.21 runs scored per team per game in 1973, 3.69 in 1972, and 3.77 in 1967. This year, run scoring is at it's lowest level since 1992.