Last night, the Astros lost, and for the first time since May 15, they find their playoff odds below 50%. They have but four remaining games to re-claim playoff position, and, I’m sure you’ve had a good sense of their struggles. A 10-16 September has dropped their playoff odds from 97% to 44%. It’s dropped their division-winning odds from 88% to 3%. It took so long to get used to the idea of the Astros advancing to the postseason, and then it felt like a given for weeks. Now people are starting to think about big-picture perspectives, like how it’s still been a great season regardless of whether it ends in a few days. That’s true, but it’s also not what Astros fans thought they’d be having to consider at the end of September.

In a certain sense, these struggles have been almost team-wide. While the position players rank third in baseball in September WAR and third in September wRC+, they’re also 22nd in Win Probability Added, owing to some lousy timing. Astros starters rank 18th in WPA, neither good nor bad. The bullpen, meanwhile, ranks 27th in WPA. The Astros have had several issues, but a once-reliable bullpen has been a big one. And within that bullpen, one arm in particular has come apart at the worst possible time.

People tend not to have bad things to say about Pat Neshek. And even here, I don’t have anything bad to say about Pat Neshek, himself. But I have bad things to say about Pat Neshek’s performance, which would qualify as dreadful even if he weren’t being used as a high-leverage reliever. Independent of context, Neshek’s September would count as lousy. Given context, you could, if you wanted to, blame Neshek for the Astros right now being out of a spot.

That’s cruel — a team is made of 25 guys. Or, in September, 225 guys, and teammates are always trying to pick other teammates up. No one player can ever sink a whole team, and focusing on September ignores all the good that Neshek did through August. But there’s no getting around the following information. Here are the league’s worst September WPAs, combining hitters and pitchers:

It’s Neshek, and it’s Neshek by a considerable margin. The next-worst Astro is Scott Kazmir, at -0.9. Then it’s Jose Altuve, at -0.6. I’m sure Altuve and Kazmir wish they would’ve done better to this point, but they haven’t come close to Neshek’s destructiveness. In September, he’s pitched 10 times. Based on the combined win expectancies when Neshek entered, you’d expect the Astros to have won 5.5 of those games. Based on the combined win expectancies when Neshek left, you’d expect the Astros to have won 3.5 of those games. (They’ve actually won just two.) As an estimate, Neshek’s September performance has been worth about -2 wins, and that’s the difference between the Astros being where they are now, and the Astros being in a very strong position with the games running out.

In five of Neshek’s 10 appearances, he’s been fine. In the other five, he’s been a wreck. Neshek has pitched in 362 career games. Of his 19 worst career appearances by WPA, five of them are out of this September. His record, briefly:

September 1: 8th inning, allowed tie-breaking home run

8th inning, allowed tie-breaking home run September 2: 8th inning, allowed tie-breaking single

8th inning, allowed tie-breaking single September 18: 8th inning, allowed lead-changing home run

8th inning, allowed lead-changing home run September 23: 8th inning, allowed lead-changing double and insurance single

8th inning, allowed lead-changing double and insurance single September 29: 8th inning, allowed tie-breaking single

The Astros lost all five of those games. In three of them, Neshek entered in a tie, so it’s not like the Astros were favored, but when a game is tied, you figure the Astros should win half the time. Neshek allowed the ties to be broken, and there weren’t any rallies.

Going one by one, here’s the pitch that so badly cost Neshek on September 1:

He fell behind a lefty 2-and-0, then he grooved a fastball down the pipe. That’s a mistake. The pitch that broke the tie on September 2:

Actually not a terrible first pitch, but it was thigh-high. And, you notice the runners. Neshek was responsible for those. He walked the leadoff batter, then when the next batter put down a sac bunt, Neshek fielded it and threw the ball away. The error came with a more damaging WPA than the single above. The error was on Neshek. Here’s the problem pitch from September 18:

Neshek got ahead, working 1-and-2, but then he hung a slider belt-high. It was supposed to be down and away, and Danny Valencia blasted it out. Moving on to September 23, we have a pair of images:

This is another mistake two-strike slider. David Freese clobbered it for a double. Then:

Two strikes, slider, over the middle. Freese had already put the Angels on top, but Carlos Perez doubled the deficit. The Astros would lose 6-5. We’ll close with September 29:

Two strikes, slider, middle, at the belt. You see that Neshek has failed, and you see the pitch that’s failed him. Neshek here inherited two outs and a runner on first. He allowed a single and a walk before allowing this other, more crippling single. This is two big hits featured in this post against Pat Neshek by Shawn O’Malley. Those are two of O’Malley’s 14 career hits.

Three bad outings against the Mariners, one against the A’s, and one — more importantly — against the Angels. This month, Neshek hasn’t had it, but what’s curious is that in August, he did have it. In August, Neshek allowed a .270 wOBA with a season-best strikeout rate. In August, he struck out 11 of 34 hitters; in September, he’s struck out three of 37. He’s also issued twice as many walks, with a hit batter on top of that. Neshek went from a strong month to a miserable month without visible warning, and while reliever fluctuation is a thing that’s known to happen, it doesn’t usually get this bad. It isn’t usually timed this poorly.

For no reason I can think of or identify, Pat Neshek has killed the Astros in September. Maybe there’s something in there going on, but if there were, and the Astros knew about it, you’d figure he wouldn’t have this kind of usage pattern. They’ve kept trying him, and on five occasions, Neshek has crippled his team’s chances of winning. For the first five months, Neshek was helpful. I doubt the Astros regret the contract. He’s not the whole reason the Astros have fallen from the top. But no player has done them more harm down the stretch. Not even Shawn O’Malley.