I've been thinking about those Wild Card leading Mariner, and how they've defied all my expectations.

Regulars to the forum know that I put a lot of faith in run differentials (the difference between a team's runs scored and runs allowed). They give you a quick and simple way to evaluate a team's pitching and defense, and their offense. Using a simple formula, differentials can be used to calculate an expected winning percentage.

But there are flaws to this approach, too. Differentials assume that all runs are equal. We all know that a single run in the 10th inning of a tie game is worth more than average.

The Mariners are 18 games over .500. We'd expect them to be only 1 game over .500.

Baseball Prospectus says that the Mariners are among the worst defensive teams in the major leagues, turning only 68.5% of ball in play into outs.

Seattle's offense doesn't seem especially impressive either but they rank 6th in the AL in OBP, and 4th in SLG. Last year's Tigers played a similar combination of OPS into a pennant.

But Seattle's pitching is nowhere close to what the Tigers had... is it?
Their starters have an unbelievably bad 1.552 WHIP with only 5.8 K/9.
Their relievers have a pedestrian 1.393 WHIP with a better 7.2 K/9.
So how have they won?

They have the best closer in baseball. They have the best setup tandem you hear nothing about in Sherril and Morrow .

Those three men (and when they are used) are the difference. In games the Mariners lose, they lose by an average of 4.057 runs. In games the Mariners win, they win by an average of 3.366 runs. Over a full season that's a huge swing.

We've talked about how bad starters aren't always bad, but inconsistent. Imagine a team staffed by Randy Johnsons and Mike Mussinas- you never know which version is going to show up. But that staff of inconsistent starters happens to be paired with the best bullpen in baseball. If the good version shows up, they make the most of it and win that game.

And the big question: (drum roll, please)
Can they keep this up for the last month of the season?

I'm worried that they can- in which case we'll soon be fighting the Angels for the wild card. For the record, in the last six years, only three teams have managed to finish the season ten or more games off the expected record: the 2006 Indians (under), 2005 D-backs (over), and the 2004 Yankees (over).