The Heroes (And Zeroes) of September

I can’t tell you why the structure of the big leagues seems to bend towards close races. On August 31, the teams on the right side of the playoff cut line were all at least 2 1/2 games ahead of their nearest competitors. All baseball has done since then is collapse into chaos. The Mets have gone 8-13 to fall into peril, though that’s nothing compared to the Tigers, who have gone 5-15 over the same stretch. The Guardians are an absurd 18-5. Playoff fortunes have ebbed and flowed mightily.

Which players have featured most prominently in those games? There are any number of ways of answering that question. You could look for the highest WAR among contenders, the worst ERA or the most blown saves. You could use fancier statistics like Championship Win Probability Added, which accounts for how much each game mattered to each team. You could use the eye test, honestly – I can tell you from how frustrated Framber Valdez has looked this month that he’s not helping the Astros.

But the closest thing to matching the way I experience baseball, as a fan, is regular ol’ win probability added. My brain doesn’t distinguish between the importance of games when a team is in the pennant race. They’re all important. You can’t lose a random game on September 7 when you’re three back in the standings; you never know when the team you’re chasing will lose five in a row. Championship Win Probability Added distinguishes between whether your team is a long shot or playing from ahead, but when I’m rooting for one of the teams jockeying for a playoff spot, I don’t do that. I don’t think I’m alone in this, either. If every game in the race is equally important to you, Win Probability Added will measure the players who have mattered most in that framework. So I’ve compiled a list of notable players from the past month in each playoff race – and as a little bonus, I threw in a few players who have either stymied contenders or gotten trounced by them.

The Best
Juan Soto, New York Mets
Soto is carrying the Mets right now. In September, he’s hitting a scorching .341/.427/.707 and doing it in big spots. He’s third in the majors with a 1.19 WPA in September (my guy Daylen Lile is first). This is what you pay someone $765 million for.

Soto has been unflaggingly brilliant down the stretch this year. His eight home runs rank second in the majors in September. His 207 wRC+ is fifth best, while his 21 RBI is tied for first (say what you will about its value as a predictive stat, RBI does a pretty good job of describing who has batted in the most runs). He’s been steady, too: The Mets have played 21 games in September, and Soto’s wRC+ has been above 100 in 15 of them. In on-field terms, that’s multiple times on base or a home run, or both. He’s a metronome, the entire New York offense. Soto has been 12.7 runs above average offensively this month. No one else has even come close. Heck, the rest of the team checks in at 3.6 runs below average in aggregate.

His biggest one-game contribution came September 1, when he put together one of his best offensive showings of the season, including a come-from-behind grand slam to put the Mets up 6-3, then a tie-breaking two-run triple that put them up 8-6 after some pitching that, well, it’s the Mets. But really, he’s been great all month. If Soto was the best player on a team that was charging up the leaderboard, this would be talked about as one of the best Septembers of the decade. Because he’s trying to hold it together while the rest of the team falls apart around him, it’s gone under the radar a little bit.

Trevor Story, Boston Red Sox
The Red Sox haven’t so much surged to a playoff spot as cruised, going 11-9 to stay above the AL Central title/last Wild Card spot fray. They haven’t done it with the hitters we were expecting before the season started, though. Rafael Devers is gone. Roman Anthony is injured, as are Triston Casas and Marcelo Mayer. Kristian Campbell hasn’t panned out yet. Instead, Story is the best of a motley crew of Red Sox leading the charge.

Nate Eaton and Rob Refsnyder are both among the team’s wRC+, WAR, and WPA leaders in September; Story’s at the top of two of those leaderboards with a .333/.371/.512 batting line and 1.09 WPA. Jarren Duran? Alex Bregman? Ceddanne Rafaela? Wilyer Abreu? They’ve each had a forgettable month, but Story and friends have picked up the slack.

Story’s best single game came on September 17, when he hit a massive game-tying single against the A’s as part of a two-hit, one-walk day. That doesn’t sound overly impressive as most impactful games go, but that’s part of what’s impressive about Story. He’s chipped in frequently enough that even without a crowning moment, he’s only a hair behind Soto’s scintillating September in WPA. He’s done a ton to push the Red Sox to the playoffs, in other words.

Hunter Greene, Cincinnati Reds
Greene is putting in a strong bid for a seat at the “best few pitchers on the planet” table this year. Since returning from injury in the middle of August, he’s made eight starts, six of them gems. He’s been so good that even an absolute disaster of an outing, five runs in two innings against the A’s, can’t keep him from the top of the WPA charts.

That game was terrible, a whopping -0.44 WPA. But Greene followed it up with a masterpiece in a game that the Reds absolutely had to have, a nine-strikeout shutout to beat the Cubs 1-0. There have only been 13 shutouts this entire season. Doing it with almost no run support from your team, down the stretch, against a playoff-caliber opponent? That’s something special.

Though that was Greene’s best game of September, an earlier start might be even more crucial. On September 7, he threw a dominant seven innings, with 12 strikeouts and only one earned run, to hold the Mets off in a 3-2 thriller. That game was crucial in more ways than one. Not only did it drag the Reds closer to the Mets, it gave Cincinnati the season tiebreaker. In the biggest spots this month, Greene has come up aces, and even when he’s come up short – last night’s thrilling duel against Paul Skenes ended in a 4-3 Reds loss – his performance has given his team a chance to win. The truly scary part for the rest of the league? This might just be who Greene is now.

Tanner Bibee, Cleveland Guardians
Bibee hasn’t been quite as incandescently brilliant as Greene this month, but that’s more a matter of how you like your aces to look than results. His 1.30 ERA across four lengthy starts, with 26 strikeouts to only five walks, has him tied with Greene for WAR in one fewer turn. Sure, everyone looks better against the White Sox, as Bibee did in a 10-strikeout shutout earlier in the month. But what really puts him on this list is that he’s done it against playoff rivals, too.

In each of his last two starts, Bibee has drawn the Tigers as the Guardians attempt to chase them down. In each start, he’s given his team six innings of one-run baseball en route to a win. Cleveland’s starters have been the key to the team’s September surge – Joey Cantillo and Gavin Williams deserve honorable mentions as well – but Bibee is the straw stirring the drink right now. He’s not getting much run support – the Guardians have scored three, four, three, and five runs in his four starts. He hasn’t needed it, though, which makes him all the more valuable; even when their offense can’t get the job done, Bibee has.

George Springer vs. the Reds
Springer could be the star of a completely different playoff story, the fight for the top of the AL East. But since we’re focusing on the teams at the fringes of the postseason, not the fight for a bye, he’s here because he so thoroughly stomped the Reds. Springer and the Blue Jays visited Cincinnati to start the month, and he singlehandedly demolished them in two of the three games.

First, a 3-for-5, two-homer day keyed the Jays to a 12-9 victory, with the second home run giving the Jays a key four-run lead late. The next day, Springer came back with another homer in a 2-for-4, two-walk performance, reaching base four straight times as the Jays turned a 5-0 deficit into a 12-6 laugher, with Springer doing a lot of the damage. That was it! He was done playing the Reds! But those two games alone hurt their chances by about as much as Spencer Steer, Cincy’s top batter by WPA, has helped them. Not bad for a cameo.

Shawn Armstrong vs. the Astros
Armstrong is having his best season as a pro. He’s worked his way to the top of the Rangers’ bullpen depth chart, now closing games and comfortably racking up career highs in saves and WAR. Early in September, the well-traveled 35-year-old faced the Astros twice in three days. First, he pitched a scoreless top of the 11th to help the Rangers win 4-3 in 12 innings. Then after a day off, he came back to lock down a four-out save with a runner on base. The Astros went 4-2 against the Rangers in September. The two times they lost, Armstrong did great work shutting them down. The playoffs are going to come down to a game or two, and Armstrong might have sealed Houston’s fate with his relieving excellence.

The Worst
Jose Altuve, Houston Astros
Sometimes it’s just not your month. Altuve has been stepping on rakes left and right this year, suffering through one of his worst seasons as a big leaguer. The decline has been especially sharp in September, when his offense simply hit a wall. Since the start of the month, he’s hitting .197/.266/.366, good for a 75 wRC+. The Astros keep putting him out there in big spots – he’s Jose Altuve, after all, one of the greatest players of our generation – but this month, he’s come up empty time and again when it’s mattered most.

Remember that 4-3, 12-inning saga from Shawn Armstrong’s blurb? Altuve had a chance to crack that game wide open in extras and popped out. In the September 7 game, he went 0-for-4, striking out when he could have tied the game with a homer. It’s not so much that he’s had one huge disaster; that’s not really how negative WPA tends to work. Instead, he’s just had a bummer of a month, and done so with a lot of runners on base at the top of an order in dire need of offense.

Framber Valdez, Houston Astros
That’s right: The two worst WPAs among playoff contenders belong to Astros. Valdez has been Houston’s ace for years, and when the 2025 campaign comes to an end, his player page will show another solid season, roughly 190 innings and about 4 WAR. It’ll be his fourth straight year with a WAR total between 3.7 and 4.4. But those numbers would have looked a lot better at the end of August. Since then, Valdez has made four starts and allowed 20 runs, with the Astros losing all four games. He’s pitched to an 8.27 ERA, walked 10 batters in only 20 innings, and generally looked completely lost.

Pitching is so weird! Valdez faded hard in the second half this year, with a 2.75 ERA before the All-Star break and a 5.63 mark after it, and declining peripherals across the board to boot. Last year, he looked cooked in the first half, then went on a ludicrous tear in August and September to finish the season strong. This year, he’s reversed the process. There are always little mechanical things to critique, small changes to your process that can lead to huge swings in results. But I don’t know how you explain being the best post-break pitcher one year, then one of the worst post-break pitchers the next year, without admitting that variance is scarily important.

Sometimes Valdez is on top of the world, and sometimes he can’t buy an out. This year, the unpurchasable outs all happened to come up in September. If the Astros miss the playoffs – and they’re currently on the outside looking in – it’ll be a strange capper to their years of October dominance. They’re close yet again, but this time, the tenured guys are the ones coming up short instead of the ones leading the charge.

Fernando Cruz vs. the Tigers, Charlie Morton vs. the Mets
I’m not really sure where to put these two, but let’s call them notable honorable mentions. Cruz and Morton barely pitched against these two playoff hopefuls. They just pitched so poorly that they accrued substantially negative WPA. In other words, if the playoff race comes down to a single game, these two might be the ones who swung it.

Cruz came into a 2-2 tie against the Tigers on September 9 and simply didn’t have it. He faced five batters, all of whom reached, the last four via walks. By the time he got pulled, the game was teetering on the brink of being over, with a 4-2 deficit and the bases loaded with no outs. The inning ended with an 11-2 Tigers lead. Wins have been hard to come by in Detroit this month, but this one was easy.

Morton, on the other hand, did plenty of damage to Detroit’s playoff hopes en route to getting DFA’ed. One of the biggest blows came against the Mets, who got their September off to a good start by shellacking Morton on the first of the month. In 3.2 innings, the Queens nine put up six runs. Even worse, this wasn’t some uncontested blowout, but a rare time in September where the Tigers offense has gotten traction. The eight runs they scored was the third most they’ve managed this month. Those runs just happened to come in a game where their pitchers gave up 10. Put Morton’s start on a different day, and he probably wouldn’t appear on this list, but he played his very worst at the worst possible time for his team. It’s a bummer – and great news for the Mets, who look like they’ll need every last win.

George Springer vs. the Astros
Wait, what?!? But it’s true! While Springer appeared out of nowhere to put a dent in Cincinnati’s playoff hopes, he did the opposite against his former team. With the AL East race up in the air, the Jays hosted Houston needing a good series. In their first game, Springer had a chance to blow things open, batting in a 3-3 tie with runners on second and third and one out. He struck out, allowing the Astros to escape the inning with a tie, before Tyler Heineman sent everyone home with a walk-off single in the 10th.

The next day, Springer was just off. He went 0-4 with a strikeout and hit into a costly double play as the Jays lost 3-2. Hey, it happens to everyone. These WPA against a single team statistics are, by their very nature, wild like that. Springer has had an excellent month. These two bad games? Just normal bad games, the kind that every hitter has. But they just so happened to come against a team clinging to slim playoff hopes, and they just so happened to come in close games. The Jays went 1-1 in those games, but if Springer had been at his best, they might have gone 2-0. Those little edges can be all the difference.