Since the end of May, when they started their climb in the National League Central Division and wild card standings, the Pittsburgh Pirates have been a model of consistency. ┬áThe Bucs’ longest losing streak of the season — five games — was way back in April. They had a four-game losing streak in mid-June and a three-game losing streak in late June. Those were counterbalanced by four four-game winning streaks between the end of May and the end of July and one five-game winning streak from July 17-22. ┬áThat consistency pushed the Pirates from a record of 20-24 on May 23 to a 64-50 record today, a 44-26 pace over nearly three months.

But the last week has not been kind to the Pirates, and it couldn’t have come at a worse time. The Bucs have dropped six of their last ten games and lost a game in the NL Central standings to the division-leading Reds, who also stumbled last week but managed to go 5-5. The Cardinals — of the +101 run differential — are lurking, just behind the Pirates in both races. And don’t forget Braves, Giants, Dodgers and Diamondbacks who are all battling with the Pirates for a wild-card spot as a fallback to a division title.

In consecutive games last week, the Pirates were done in by two different players who each posted games in the Top 250 in Win Probability Added this season. On Thursday, the Pirates were battling the Diamondbacks at home in the last game of four-game series. The Bucs had won two of the first three games and were ahead 3-2 in the 6th inning of final game. Wandy Rodriguez, acquired from the Astros before the trade deadline, was on the mound for the Pirates, trying to preserve the one-run lead. Rodriguez retired Justin Upton to start the 6th, but gave up a single to his former Astros teammate Chris Johnson, who’d also been traded at the deadline, to the Diamondbacks. Rodriguez then got Chris Young on a pop fly, bringing Wil Nieves to the plate.

Nieves is a veteran back-up catcher, meaning he’s played at the major and minor-league level for the Padres, Angels, Yankees, Nationals, Brewers, Braves, Rockies, and now, Diamondbacks. Colorado designated Nieves for assignment on August 1. By August 6, he’d signed with the Diamondbacks. Last Thursday’s game against the Pirates was his first in an Arizona uniform. With Chris Johnson on first, and two outs, Nieves stepped to the plate and did this:

Nieves’ home run put the Diamondbacks ahead to stay, sending the Pirates to their fifth loss in ten games. Nieves posted a .386 WPA for the game, the 207th best of the season.

The next day, the Pirates welcomed the Padres to town for a three-game weekend series. Sure, the Padres were sitting at 49-64, but were riding a four-game winning streak. By the 4th inning, the Pirates had built a 7-1 lead behind home runs by Garrett Jones and Travis Snider and a two-run single by Pedro Alvarez. James McDonald was on the mound for the Bucs, he of the 2.37 ERA in the first half.

But the second half of the season has been a different story for McDonald, who’s struggled with walks and the long ball. Fittingly, he walked Cameron Maybin with one out and bases empty in the top of the 5th. John Baker singled, moving Maybin to second. With the pitcher’s spot due up, Padres manager sent pinch hitter Jesus Guzman to the plate. He doubled, scoring Maybin and Buck. Alexi Amarista (the Padres’ version of Jose Altuve) singled, scoring Guzman. Evereth Cabrera’s single moved Amarista to second, bringing Chase Headley to the plate with the Pirates clinging to a 7-4 lead.

Tie game.

The Pirates re-took the lead in the 6th on a run-scoring single by Rod Barajas. But the Padres came storming back. And again, it was Chase Headley. With two outs and bases empty, reliever Tony Watson walked Amarista, bringing Headley to the plate.

That put the Padres ahead to stay. They beat the Pirates by the final score of 9-8. Headley posted a .671 WPA for the game, the 28th highest WPA of the season.

The Pirates open a crucial four-game series tonight against the Dodgers. They’ll need to be careful with Matt Kemp, of course, but they best not lose site of the bottom of the Dodgers’ batting order. You just never know who’s going to have a big game.