The A’s Are Being Led From the Back

Last Tuesday, the A’s played probably the most frustrating game of their season. Facing the first-place Astros in Houston, the A’s erased a 4-0 deficit in the top of the ninth. In the 11th, they pulled ahead on a two-out home run, getting the chance to hand a lead to Blake Treinen. The tying run scored on a fielder’s choice, with Jonathan Lucroy unable to handle a throw home. The losing run scored on a tapper that went about five feet, after Lucroy threw the ball away. It was a tough inning for Lucroy, and it was a rough game for Oakland to stomach, because they’d had the Astros just where they’d wanted them. While the A’s had been hot, you never know which loss might get under a team’s skin.

The A’s came back and beat the Astros the next day. They beat them again the day after that, and then they took two of three in San Francisco. Where just weeks ago it looked almost impossible, we’ve gotten to the All-Star break and now we have a wild-card race. The A’s are catching up to the Mariners, and while every run is a function of a number of players, Oakland’s two standouts are at the back of the bullpen.

Momentum is a funny thing. Statistically, we know it should almost always be dismissed, but it can create a hell of a narrative. For something with so little evidence, it’s strangely persuasive. Just think about, I don’t know, last week’s A’s. They lost that horrible game to the Astros. Then they recovered immediately. You wouldn’t think they’d be able to do that. Baseball players, though, are good at flushing away a bad experience. It’s kind of a part of their training.

So you can look at this in one of two ways. In one way, we’re at the All-Star break, and the Mariners lead the race for the second wild card by three games. In the other way, sure, the Mariners lead the race, but over the course of the past month, the A’s have posted baseball’s best record, at 21-6. They’ve gained ten games on the Angels over that stretch, and they’ve gained eight games on the Mariners. When the A’s were 34-36, their odds of making the playoffs were about 3%. Now they’re about 31%. And our brains want to extrapolate the rest of the comeback — it’s easy to imagine the A’s pulling even. They now have a better run differential than the Mariners do.

The truth is that the Mariners do still have the advantage. They still remain something like the 2-to-1 favorites. There’s uncertainty, though, is the point. The AL playoff picture isn’t settled after all. The A’s and Mariners will play each other another ten times. So we should consider how we got here. What forces have driven the A’s to success?

The first thing you notice is that the A’s have had an above-average lineup. This was true last year in the second half, so it’s not very surprising, because nearly every player who made a meaningful impact in last year’s second half came back. According to our WAR leaderboards, both Jed Lowrie and Matt Chapman this year have been top-30 position players. Now that he’s healthy again, Lowrie has experienced a career renaissance. And Chapman is a two-way threat. He hits for power, but also, he ranks first among all players in 2018 in Defensive Runs Saved, and he ranks second in Ultimate Zone Rating. Over Chapman’s 165 career major-league games, he has a +40 DRS, and a +19 UZR. He’s as good a defender as a third baseman can be.

So Chapman has changed the Oakland infield, similar to the impact that Francisco Lindor had in Cleveland. If Oakland has a star to build around, Chapman is it. Beyond him, the lineup does go deeper. And he’s not the only good defender on the club. But allow me to advance to a table. What’s really been driving Oakland’s success? It’s not so much the patchwork rotation. That’s a rotation that lost Jharel Cotton and A.J. Puk before the season even began. Here is a table of the first half’s top ten relievers, according to WPA.

The A’s have two relievers in there. So do the Diamondbacks, and so do the Brewers. For Oakland, Lou Trivino is in eighth place. And Blake Treinen is in first, even though, because of the way WPA is calculated, he took the hit for last Tuesday’s defensive collapse. When the A’s lost that game to the Astros, Treinen’s WPA went down by 0.80 points. If not for that, he’d be the leader by an even greater margin. Trivino and Treinen are a huge reason why the A’s are where they are, and here’s a different way of visualizing it. Here’s a plot of all 30 teams, showing the combined WPA for their top two relievers:

If you want to read more about Treinen becoming so dominant, here you go. Treinen has been around for a number of years. Trivino is a rookie. You might not know about him, because he began the season in Triple-A. I could show you statistics, or I could show you a GIF. I prefer to show you a GIF.

Over a combined 92.1 innings, Trivino and Treinen have allowed a .209 wOBA and a 26 ERA-. You’d be right to point out this level of success is basically impossible to keep up. Their combined FIP- is 60; their combined xFIP- is 70. But to this point, Oakland’s bullpen tandem has been nearly unbeatable. I don’t know why it wouldn’t continue to be very good. Both relievers have been able to generate swings and misses, and Trivino might only improve as he learns more about how his stuff works at the big-league level. The A’s have effectively been closing games early. The shutdown back of the bullpen has reduced the burden on the entire rest of the staff.

Moving forward, the A’s do still have ground to make up. They do still have a thin rotation, that doesn’t have an equivalent of the Mariners’ James Paxton. The A’s are presumably looking to buy, yet it’s a pretty thin market, assuming they’re not interested in, say, Manny Machado. Odds are, the A’s will move to just increase their depth. Add a mid-rotation starter, or a mid-inning reliever. This team remains a wild-card underdog. To say nothing of its chances if it actually made it to the elimination game.

But there are two encouraging things to point out, I think. One, by our numbers, the Mariners have the tougher remaining schedule. This mostly comes down to the fact the Mariners will face the Astros another 13 times, while the A’s have only another six such matchups. And two, while Edwin Diaz has been the Mariners’ version of Treinen, more or less, Diaz is also tied for the major-league lead in appearances. He leads baseball with 19 games on zero days’ rest. Treinen’s at 11, and Trivino’s at 9. Diaz has been vitally important to the Mariners’ close-game success, but there’s a chance he could end up fatigued down the stretch. Treinen and Trivino might have more in the tank. A dominant early reliever or bullpen might not remain so dominant in the event it’s overworked. It’s something to keep an eye on as the month of August approaches.

From the A’s perspective, I think they knew they were an organization on the rise, but the team got hot at just the right time. Had the hot streak been delayed any more, it might’ve made sense to put Treinen on the market. As a shutdown reliever available at the break, he could’ve brought back a prospect haul. As is, in large part because of Treinen, the A’s have made up enough ground to act like a buyer. It’s always more fun to buy than to sell. And in the course of only one month, the A’s have changed their own direction.