Over the course of a season, a baseball team will play a lot of games. Some of those will be against good teams! Some of those will be against bad teams. The games against good teams are supposed to be the tests. The games against bad teams are supposed to be the gimmes. There’s a variety of things people say about those games. Those are the games that “good teams are supposed to win.” A team that stumbles might have “overlooked” the opponent, with a tougher one coming up. Then there’s the line about a team that “plays down to the competition.” People have a lot of things to say about losses to bad teams. People have a lot of things to say about sports.

I want to steer your attention to something. For years, Baseball-Reference has provided a split: stats against teams .500 or better, and stats against teams under .500. I think a lot of us have known about this, but I’m not sure I’ve seen the information cited more than a handful of times. It’s a rough split, but it’s a handy split — teams .500 or better tend to be the good teams, and teams under .500 tend to be the bad teams. Let’s settle for the rough split, for now. So, now I want to steer your attention to the Mariners and the Angels.

This is going to be all about wins and losses. Below, a chart of 2014 data, that ought to be self-explanatory. On the y axis, win percentage against .500+ teams. On the x axis, win percentage against worse teams than that. Naturally, the numbers on the x axis are mostly higher than the paired numbers on the y axis.

So, obviously, there’s a relationship. Better teams will win more games against both sets of opponents. Worse teams will lose more games against both sets of opponents. But, look at that red dot, well above the line. And look at the red dot on the far right, separated from the rest of the pack. Here we see the Mariners, and here we see the Angels, and they’ve so far gone in two different directions.

This table might give you a better sense of things:

Team Win% vs. Good Win% vs. Less Good Difference Mariners 0.594 0.485 0.109 Reds 0.481 0.475 0.006 Tigers 0.541 0.563 -0.022 White Sox 0.448 0.471 -0.023 Cardinals 0.529 0.559 -0.030 Marlins 0.469 0.507 -0.038 Brewers 0.508 0.547 -0.039 Padres 0.459 0.508 -0.049 Twins 0.418 0.468 -0.050 Braves 0.481 0.540 -0.059 Cubs 0.425 0.485 -0.060 Giants 0.509 0.571 -0.062 Rangers 0.354 0.429 -0.075 Yankees 0.479 0.554 -0.075 Astros 0.402 0.481 -0.079 Phillies 0.425 0.508 -0.083 Blue Jays 0.473 0.556 -0.083 Orioles 0.545 0.633 -0.088 Rays 0.438 0.560 -0.122 Royals 0.500 0.623 -0.123 Pirates 0.451 0.582 -0.131 Indians 0.452 0.587 -0.135 Athletics 0.513 0.655 -0.142 Dodgers 0.475 0.625 -0.150 Rockies 0.314 0.478 -0.164 Red Sox 0.382 0.551 -0.169 Diamondbacks 0.319 0.507 -0.188 Mets 0.382 0.571 -0.189 Nationals 0.448 0.658 -0.210 Angels 0.487 0.754 -0.267

The Angels have won just under half their games against good teams, and they’ve won three-quarters of their games against bad teams. They’ve done what you’d expect, except to an extreme degree. All but two teams have been worse against good opponents than bad opponents. The Reds have been basically even. The Mariners have been freaks.

To this point, the Mariners have gone 33-35 against sub-.500 opponents. Yet, they’ve gone 41-28 against superior opponents, and as I write this very sentence, they’re narrowly beating the A’s. The Mariners have a winning-percentage difference of 109 points in the opposite direction from the norm, and they’re separated from second place by more than 100 points. The Mariners would serve as an example of a team that plays up to opponents and down to other opponents. They’ve handled themselves against the A’s, Braves, Royals, and Angels. Within the past couple weeks they’ve lost series to the Phillies and the Rangers.

Going back to 1914 gives us 2,184 team seasons. In 2,023 of those, the given team had a lower winning percentage against .500+ opponents. Only 11 teams ever have finished with a winning-percentage difference of at least 100 points in the unusual direction, like the Mariners are on pace to do. Right now, the Mariners’ difference would rank sixth-greatest, ever. In 2010, the Cardinals finished with a difference of 137 points, which ranks No. 1. Then you’ve got the 1932 Reds, the 1979 Giants, the 1998 Twins, and the 1918 Pirates. The Mariners have done something not unprecedented, but they’ve done something really weird.

Of course, there are facts, and then there are meaningful facts. It’s tempting to want to try to explain this. We want to try to explain everything. The positive spin would be that Lloyd McClendon gets his team amped up for big games. The negative spin would be that McClendon doesn’t sufficiently get his team amped up for lesser games. You can’t determine whether it’s a good thing or a bad thing, and the key point here is understanding randomness. There’s no rational reason why a team might over-perform against quality opponents, and under-perform against weaker opponents. Not to such an extreme degree.

And, yeah, it turns out to be mostly random. Let’s take the 15 teams who finished with the greatest positive differences. They averaged differences of 107 points, in favor of playing stronger opponents. The year before, they were 193 points worse than that. The year after, they were 215 points worse than that.

Now let’s take the 15 teams who finished with the greatest negative differences. They averaged differences of 360 points, in favor of playing weaker opponents. The year before, they were 222 points better than that. The year after, they were 196 points better than that. Those 2010 Cardinals? That year, they were better against good teams by 137 points. In 2009, they were worse by 151 points. In 2011, they were worse by 88 points. The problem with breaking things down by year is that teams aren’t identical in consecutive seasons, but you’d figure that an ability like this wouldn’t completely erode, if it were real.

Instead, it seems to be in the same family as clutch, or hitting with runners in scoring position. There are clutch performances, but there generally are not consistently clutch performances. There are a lot of numbers we can use to describe the past, but only some of those numbers can be used to try to see into the future, and it’s important to understand which numbers go where. Maybe it’s not actually important, for us on the outside, but if you’re going to know something, you might as well also try to know what it means. The Mariners, so far, have been a weird-ass team, and the Angels have been a differently weird-ass team, but you’d still prefer the Angels going forward, because you mostly care about overall performance and certainly no one’s going to go into October unmotivated.

The benefit of numbers you don’t expect is that you have to think about them, and in so doing you might develop some new connections. But not every number means what it seems. Numbers aren’t liars, but sometimes they’re more than happy to just string you along for the hell of it.