On Wednesday night, the Mariners pounded out 21 runs, the largest offensive outburst of any team this season, and they did it against the Rangers, the team with the AL's best record and the majors' best run differential. After a 1-2-3 first inning against Texas starter Derek Holland, they scored eight runs and sent 13 batters to the plate in the second inning, with a three-run homer by Dustin Ackley and a two-run shot by Jesus Montero the biggest blows. They followed that with another eight runs during a 13-batter third inning featuring Justin Smoak's three-run homer. By the fourth inning the score was 17-0, and even with some offensive firepower unleashed by the Rangers, the Mariners still had more in reserve, as Smoak added another three-run shot. Final score: 21-9.
What's remarkable is that the Mariners came into the game scoring 3.79 runs per game on .229/.290/.362 hitting, numbers that ranked second-to-last in the league across the board. The outburst pushed them to 10th in scoring at 4.11 runs, though they're still second-to-last in all three slash stats. As you'd expect, teams with offenses that meager don't generally pile up runs in such fashion. Since the beginning of the 1993 season, when the majors expanded to Colorado and Florida, 29 teams (not including these Mariners) have scored 21 runs in a game, four of them doing so twice. Of those teams, the only one to average fewer than 4.50 runs per game was the 2004 Royals, who scored 4.44 per game in a league where 5.01 was average. Collectively, the 21-run teams averaged 5.24 runs per game, though to be fair, most of that occurred when league scoring levels were higher than they are now.
Furthermore, those 29 teams rolled up a collective .530 winning percentage, with just 11 finishing below .500; meanwhile, 13 of them won 90 or more games. The aforementioned Royals were by far the worst, at 58-104 (.358 winning percentage), followed by the 2009 Indians at 65-97 (.401). If this year's Mariners, now 23-30, don't improve from their .434 winning percentage, they'd rank as the third-worst.
What are the odds of a team as bad as the Mariners scoring 21 runs in a game?
On Twitter, a couple of intelligent statheads offered their takes on Wednesday night. @Toirtap (keeper of the Walk Like a Sabermetrician blog), estimated the probability of a team scoring 3.8 runs per game suddenly erupting for 21 at 0.0049 percent, or one in 20,573 games. @Sky_Kalkman (of Beyond the Box Score) used Tom Tango's Linear Weights Generator, which employs a complex mathematical model called a Markov Chain, estimating the chance of 21 or more runs at 0.0027 percent, or one in 37,037 games. Neither estimate accounts for the opponent or the ballpark, and empirically, both appear may be on the low side; in a season with 2,430 games, we would expect to see an offense as bad as the Mariners reaching 21 or more runs somewhere between once every 8 to 15 seasons, when in fact we've got one in 20 seasons (two shortened by the 1994-1995 strike, and this one incomplete, of course).
As bad as this Mariners offense is, it can't hold a candle to the eyesores they've paraded in recent years. The 2010 Mariners scored just 513 runs (3.17 per game), the lowest full-season total since the designated hitter was adopted in 1973; the last team to score fewer was the 1971 Padres, at 486 (3.02 per game). The 2011 Mariners managed just 556 runs (3.43 per game). Even before their onslaught, the 2012 model was on pace for 614 runs, a 10 percent increase over last year.
But make no mistake, this lineup is awful. Of the nine regulars, three (Miguel Olivo, Brendan Ryan and Chone Figgins) have batting averages below .200, and four have on-base percentages below .300 (that trio and Smoak). Ryan and Figgins are both slugging below .300, while Kyle Seager, Michael Saunders and Montero are the only ones slugging above .400. Seager's .273 True Average, via a .278/.319/.466 line, is the highest among regulars, just 13 points above the defined league average, while Montero, Ackley and Saunders are between one and five points above average, with everyone else below average.
The bigger question is how did the Mariners, who appear to be headed for their fourth losing season out of five, get to be so lousy? Start with a trio of heralded prospects who have significantly underdelivered. Even after a night in which he went 3-for-4 with a double and a homer, Montero, whose bat drew comparisons to Miguel Cabrera and Frank Thomas from prospect experts before he was acquired from the Yankees in the Michael Pineda trade in January, is hitting just .257/.300/.429 and has been worth 0.0 WARP, exactly replacement level. Smoak, despite the two homers, is hitting .231/.278/.396 this year, and .234/.307/.398 in 805 plate appearances since being acquired from Texas in the Cliff Lee deal in mid-2010. Saunders, the 11th pick of the 2004 draft, is hitting .247/.321/.406 as the regular centerfielder, which is at least better than the .196/.263/.306 he hit in 635 PA from 2009 to 2011. All three made Baseball America's top prospect lists in multiple years, and all have generally disappointed, though at least the 22-year-old Montero is still a rookie. Ackley, a 24-year-old chosen second overall in the 2009 draft, could be included in this group as well. He hit .273/.348/.417 after debuting in mid-June last year, but has fallen off to .251/.320/.372 in 2012.