This isn’t my own subjective interpretation. When you throw around a word like “favorites,” that opens the door to opinion-based writing, but I have numbers on my side. Sweet, sweet, precious numbers. Look at the following table. You have our preseason projected win totals, and our current projected win totals, which take into account everything that’s happened.

Projected Wins, 2016 AL West Team Wins, Before Wins, Now Angels 81 74 Astros 88 82 Athletics 79 77 Mariners 82 86 Rangers 79 81

We liked the Astros a lot. Still do, but they’ve done themselves considerable harm. After the Astros, there was a group of four teams, all vying for second or last. The Mariners have emerged through the early going, and now they’re well out in front. Sure, that’s just us, but if it makes you feel any more trusting, PECOTA agrees. Projections still like the Astros, but the Astros are way behind the Mariners, just because of the games in the books. So the Mariners find themselves in a great divisional position. Getting to the point faster: This.

A lot has gone into that picture. Let’s talk.

This isn’t the Mariners doing everything themselves. We’ll get to them, but look at the context. The Astros are already seven and a half games out, which is a huge deficit, even with so many games left to go. The A’s looked like they could be decent, but they’re in a rut, with under-performance and injury problems. The Angels are a disaster zone, with Garrett Richards gone, and Andrew Heaney probably gone, and Andrelton Simmons hurt, among other things. The Rangers have mostly hung with the Mariners, maintaining a small gap, but the overall race has thinned out. There are just fewer teams in the division that look legitimate.

And the Mariners have simply been good. By wins and losses, they’ve been good. By expected wins and losses, they’ve been good. Back on April 12, the Mariners lost a second game to the Rangers, ensuring a lost series. They haven’t lost a series since, and they’ve already won this current series against the Rays, Wednesday’s result be damned. The Mariners are rolling, seemingly emerging as an actual league contender.

Whenever you examine a whole team, you can look at dozens of individual reasons for why the team is where it is. The Mariners wouldn’t be where they are were it not for Robinson Cano’s bounceback campaign. They’ve been given a substantial lift by the breakthrough performance of Taijuan Walker. Every single player plays a part, so every single player has a story. I’m not looking to be that comprehensive. Not on May 11. I just want to show you two critical things, two factors that have made a difference. How have the Mariners become favorites? In large part, you could credit two things. One of them makes sense! One of them is insane.

We’ll start with the one that makes sense. There are a lot of ways to try to measure team defense. Obviously, there’s UZR, and there’s DRS, but on the team scale, I like simple BABIP. Or, ever so slightly more complex, SLGBIP — slugging percentage on balls in play. Sure, you lose a little bit of information about batted-ball quality, but you don’t have to worry about shifts being ignored. Take it for what it is. I looked at SLGBIP allowed in 2015, and SLGBIP allowed so far in 2016, and then I calculated the difference. That’s what’s shown below.

What you’d like to see is a negative number. A negative number means year-to-year improvement. The White Sox have made themselves way better in this regard. So have the Cubs. And, so have the Mariners, who are there between the Cubs and the Reds. A year ago, by this measure, the Mariners were about average. This year, they’re tied for second. If this is adequately capturing defense, then the Mariners have been playing much better defense.

Which, yeah, sure. Robinson Cano isn’t playing through crippling pain. Leonys Martin is in the middle of the outfield. The personnel can explain it, and so can how the personnel has been used. As you know, the Mariners have a new coaching staff, and a new front office, and all those new people brought a new philosophy. At least, a philosophy that’s new to the Mariners. Based on our own splits, last year 537 balls were put in play against the Mariners with some kind of shift on. The pace this year is for 1,694. The team has been extremely aggressive shifting, and it would appear the shifts themselves have also been more successful. Maybe they won’t remain successful to this extent, but there’s unquestionably more of a defensive plan in place. And moving forward, Nelson Cruz is expected to play less and less right field. That could help even more.

The Mariners’ strong start has been fueled in part by better glovework. That shouldn’t be a surprise, because better glovework was a priority. I imagine the defense will remain pretty good. This has been critical, but then, so has the bullpen. I mentioned that something has been insane. The Mariners’ bullpen hasn’t just not been a liability. It’s been maybe the best bullpen. I don’t know.

As I write this, the bullpen has a collective 2.37 ERA, which is tied for the lowest in baseball. The FIP is third-lowest in baseball. The xFIP is fifth-lowest in baseball. The WPA is tops in baseball, by a lot. How surprising is this? Here’s maybe the best way to put it. We projected the Mariners to have baseball’s 27th-best bullpen, with a 1.6 WAR. The bullpen has already been worth exactly 1.6 WAR.

Now, the Mariners did plenty of offseason bullpen shuffling. By the end, you could see how the unit could conceivably be good enough. But look where we are now: Joaquin Benoit is on the disabled list, and so is Charlie Furbush, and Evan Scribner, and Tony Zych, and Ryan Cook. The bullpen has that 2.37 ERA. Based on playing time and preseason projections, we’d have expected this very bullpen to have a 3.79 ERA. That would mean plenty of extra runs, in the higher-leverage, later innings.

The Mariners bought low on Steve Cishek, and so far, so good. The same could be said for Joel Peralta, who signed for nothing. Nick Vincent has been phenomenal since also being acquired for nothing, at the end of March. Vidal Nuno has taken to relief work well. There’s an old belief that relievers are unreliable and unpredictable. People exaggerate it — relievers aren’t that unpredictable — but this year’s Mariners are an example of why some people will forever find it silly to invest too much in a bullpen. It can feel at times that relief work is random, and regardless of the truth, the Mariners have ridden an unlikely bullpen assortment into first place.

And, they say Benoit is about ready to come back. Furbush is throwing, and Zych will resume throwing before long. Cook and Scribner look like second-half reinforcements. Somehow, this bullpen could end up looking deep. Alternatively, it could still go off the rails, but it’s held it together for five weeks. The Mariners’ record reflects that.

The Mariners’ record reflects plenty. There’s more depth on this roster. Cano, again, is healthy. Walker seems like he’s breaking out, and players who were bought low are mostly regressing in the right directions. A record is a function of innumerable variables, but two prominent variables for the Mariners have been better defense and better relief work. The defense, it feels like you can trust. The relief work is a mystery, but it kind of always is. Last year’s Mariners showed what can happen when a bullpen falls apart. This year’s Mariners have showed what can happen when a bullpen gets its shit together. No, we couldn’t have easily seen this coming, but what fun would that have been?