American League Dynasties and Doormats

Here are the records of the best American League teams over the years, as measured by centered, nine-year won-lost average (to enlarge, right-click and select "open link in new tab"):

Derived from statistics available at Baseball-Reference.com. The series begins in 1905 (the middle year of the span 1901-1909) and ends with 2004 (the middle year of the span 2000-2008).

Two points: (1) The Yankees have assembled the longest and strongest dynasties, most notably, the one that began in the 1930s and lasted until the 1960s. (2) Only five of the AL's fifteen franchises* have been strong enough, at one time or another, to have the league's best record over two or more consecutive nine-year spans.

The "other" teams have mustered leadership for only a single season. Those teams, from left to right on the graph, are the Indians, Tigers, and White Sox (on two occasions, separated by 30 years).

Will a new "dynasty" emerge, or will the Yankees halt their downward slide and reassert their dominance over the American League? Stay tuned.

As for the doormats, here are the records of the worst American League teams over the years, as measured by centered, nine-year won-lost average (to enlarge, right-click and select "open link in new tab"):

Derived from statistics available at Baseball-Reference.com. The series begins in 1905 (the middle year of the span 1901-1909) and ends with 2004 (the middle year of the span 2000-2008).

Two points: (1) Three franchises -- the Athletics, Browns/Orioles, and Red Sox have endured long stretches of ignominy and enjoyed long stretches of glory. (2) Ignominy has been spread more evenly than glory: Ten of the AL's fifteen franchises* have been weak enough, at one time or another, to have the league's worst record over two or more consecutive nine-year spans.

The "other" teams have served as doormats for only a single season. Those teams, from left to right on the graph, are the White Sox, Angels, and Royals.

THE FOLLOWING PORTION WAS REVISED AND EXTENDED ON 10/04/08

Finally, I have postulated elsewhere ("Has Baseball Become More 'Competitive'?") that baseball has become increasingly competitive since the advent of expansion in the 1960s and free agency in the 1970s. I have revised that assessment, in view of the above graphs. In particular, it seems that the gap between best and worst teams had been narrowing (generally, though not monotonically) since the earliest days of the American League until about 1980. That observation caused me to take another look at the third graph in "Has Baseball Become More 'Competitive'?":



I now see that the American League had been growing steadily more "competitive" (if not always perceptibly so) from its earliest days until just before the onset of free agency in 1976 and the 1977 expansion round. Since then, there has been (on balance) no perceptible gain, and perhaps a bit of a setback, which may be due to the expansions of the 1990s.
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* The fifteen franchises are the original eight -- Baltimore Orioles (previously Milwaukee Brewers and St. Louis Browns), Boston Red Sox, Chicago White Sox, Cleveland Indians, Detroit Tigers, Minnesota Twins (previously Washington Senators), New York Yankees (originally Baltimore Orioles), Oakland Athletics (previously in Philadelphia and Kansas City) -- and seven expansion franchises --Kansas City Royals, Los Angeles/Anaheim Angels, Milwaukee Brewers (originally Seattle Pilots, now in National League), Seattle Mariners, Tampa Bay Devil Rays, Texas Rangers (previously the expansion Washington Senators), and Toronto Blue Jays. See this post (scroll down) for a detailed recounting of franchise histories.