I started by grabbing yearly pitching totals for each franchise from the franchise encyclopedia section of Baseball-Reference.com (a sample). Unfortunately those pages don't include thirds of an inning, but that won't change the results much anyway. In case of ties, though, I've gone and checked the relevant team pages. After getting all those numbers, it's easy to sort by innings pitched per game.
The bottom of the list is dominated by teams from the 19th and early 20th centuries. A simple reason for this games shorted because of darkness. Fields also weren't engineered as well as they are today, meaning inclement weather could shut games down much more quickly.
The two major league teams that averaged the fewest innings pitched per game folded shortly after beginning play. The 1884 St. Paul White Caps and 1884 Wilmington Quicksteps, both members of the Union Association, averaged 7.89 IP/G. St. Paul went 2-6 while Wilmington went 2-6-1 while Wilmington went 2-16. The 1884 Richmond Virginians, part of the American Association, were third from the bottom, averaging 8.04 IP in their 46 games.
It should come as no surprise that the team with the lowest average over a full season also owns the record for most losses in a season. The 1899 Cleveland Spiders, the best 20-134 team in baseball history, averaged a merciful 8.21 innings pitched per game. Just above them were the 1890 Baltimore Orioles and five Washington teams from the 1890's.
Turning to more modern teams, here are the bottom ten since expansion in 1961:
- 2005 Royals, 8.72 (1413.1 IP/162 G)
- 1961 Athletics, 8.73 (1415.0/162)
- 2001 Pirates, 8.74 (1416.1/162)
- 1979 Blue Jays, 8.75 (1417.0/162)
- 1978 White Sox, 8.75 (1409.0/161)
- 1983 Mariners, 8.75 (1418.0/162)
- 2005 Rockies, 8.76 (1418.2/162)
- 1985 Rangers, 8.76 (1411.0/161)
- 2006 Orioles, 8.76 (1419.0/162)
- 1997 Phillies, 8.77 (1420.0/162)
1999 Padres, 8.77 (1420.0/162)
2003 Rockies, 8.77 (1420.0/162)
The other extreme has a mix of different eras. The top spot is held by the 1918 Washington Senators, a team that averaged a stunning 9.45 innings pitched over their 130 games. They went 72-56-2, finishing third in the league. There must have been a lot of extra baseball in Washington that year. The 1876 Louisville Grays are second, averaging 9.32 IP/G despite giving up just under 5 runs each game. The 1876 New York Mutuals took third at 9.30 IP/G while allowing over 7 runs each day. The 1969 Twins are the highest team since expansion, throwing 1497 innings on the year, or 9.24 per game. They finished 97-65 and played eleven games that lasted 13 or more innings.
Here are the top ten averages since expansion:
- 1969 Twins, 9.24 (1497.0 IP/162 G)
- 1973 Dodgers, 9.20 (1491.0/162)
- 1967 White Sox, 9.20 (1490.0/162)
- 1988 Athletics, 9.19 (1489.0/162)
- 1996 Padres, 9.19 (1489.0/162)
- 1982 Dodgers, 9.19 (1488.0/162)
- 1985 Mets, 9.19 (1488.0/162)
- 1964 Yankees, 9.18 (1506.0/164)
- 1972 Padres, 9.17 (1403.0/153)
- 1972 Reds, 9.17 (1412.0/154)
Wondering about the high and low teams in 2008? It turns out three teams averaged at least nine innings pitched per game, but one of them isn't one of the teams that totaled over 1458 innings. The Mets led the majors with 1464.1 innings pitched in 162 games, or 9.04 IP/G. The Cubs were next with 1450.2 in 161 games, or 9.01 IP/G. Finally, the Padres wound up at 1458 1/3 IP, just a hair over 9.00 IP/G. The bottom three teams were the Orioles, Astros, and Diamondbacks, averaging 8.83, 8.85, and 8.86 innings per game, respectively. The major league average was 8.93 IP/G. The major league average has hovered between 8.90 and 8.93 since 2000.