Since 2007, the Seattle Mariners' run-scoring abilities have been in free-fall. They scored 794 runs that season, winning 88 games.

Slowly -- actually, not so slowly, come to think of it -- the Mariners quit producing runs. They scored 671 in 2008, 640 in 2009 and completely fell off almost all charts with 513 runs scored in 2011, in a 101-loss season.

That was the fewest runs scored by an American League team in a non-strike season since the Angels had 498 in Year of the Pitcher, 1968.

Seattle improved a bit in run-scoring in 2011, with 556 of them. But even that team was hardly an offensive juggernaut; it scored 10 or more runs just four times (comparison point: the 2011 Red Sox, who led the majors with 875 runs, scored 10 or more runs 25 times).

That's why Wednesday night's Seattle scoring outburst -- 21 runs against the Texas Rangers -- came as such a surprise. It's 10 percent of all the runs Seattle had scored the entire season before Wednesday (218). It's 11 runs more than their previous season high, although Seattle had accomplished that 10-run feat twice in the previous two weeks, including just the day before against Texas.

They had back-to-back eight-run innings in the second and third and led 17-0 going into the bottom of the fourth. They hit four home runs (Jesus Montero, Dustin Ackley and a pair by Justin Smoak); every starting player had at least one hit, one run scored and every Mariner but Chone Figgins had at least one RBI. (Why is that last fact not a surprise?)

Seattle's offensive output fell one run short of the franchise record, set April 29, 1999 against the Detroit Tigers. It was the most runs scored in a game since the Yankees scored 22 against the Athletics August 25, 2011, and it was the 37th game since 2000 in which a team scored 20 or more runs, an average for all of Major League Baseball of about three per season. It was the first time a Rangers team had allowed 20 or more runs since September 30, 2000, when they gave up 23 to the A's.

So this sort of thing doesn't happen often for either of these clubs. For the Mariners, it's an extremely rare event, worth noting and remembering. It could be a decade or more before Seattle crosses the 20-run barrier again.