PITTSBURGH — For the 13th time this season, the Pirates entered the final game of a series with a chance to sweep their opponent.

For the 13th time this season, they failed to do so. This time it was against the Washington Nationals. Right-hander Bryse Wilson, the Pirates’ starter, gave up two homers and four runs in the fourth inning, setting up the inevitable 6-2 loss.

Obviously, the lack of a sweep during the whole season is not the Pirates’ most glaring issue in 2021. They are now 52-91, with each loss bringing them closer to the 100-loss mark. They will almost certainly finish the season with one of the five worst records in baseball.

Whether or not they sweep the Nationals in a meaningless September series is of little importance to the larger picture. What makes it notable is just how rare it is for a team to go an entire season without sweeping a series.

Every team in baseball has done it this year except the Pirates. As a franchise, the Pirates have never gone an entire season without sweeping someone. In the history of baseball, there are just six instances in which a team has gone a whole season without sweeping an opponent.

So, yes, it may be true that the event doesn’t change anything or matter in the long run. It is, however, another thing to outline just how rough this specific season has been for the Pirates.

“I didn’t even personally know that was a stat that we had. That’s unfortunate,” shortstop Kevin Newman said. “Obviously, you want to get those wins against any team that you can. But we look at the positives and say that’s a series win. And, really, stringing those together is kind of the goal. Obviously, the icing on the cake is a sweep. But series wins is what gets you deep into the season and puts you in a good spot to potentially go into the postseason. So that’s kind of how you look at a series and how to progress.”

As far as what is important to the Pirates in the coming seasons, Wilson’s struggles were substantively disheartening. The 23-year-old righty has been good since coming to Pittsburgh at the trade deadline.

Through his first six starts as a Pirate, he had not allowed more than four runs in any start. In all but one of his outings, he had pitched at least five innings. By those metrics, Sunday was Wilson’s worst start of the season.

It began in the second inning, when Luis Garcia took Wilson deep to the first row of seats in right-center. Wilson shrugged that off and did not allow another run through the third inning. The fourth was where it all came unglued, though.

Wilson got the first two outs in the inning, then allowed a solo homer to Alex Avila, a double to Adrian Sanchez, a single to opposing pitcher Patrick Corbin and a three-run bomb to Lane Thomas to cap it all off. Wilson pitched just 4 1/3 innings, giving up seven hits and five earned runs with no strikeouts.

“Yeah, I felt like I was drifting a little bit in my mechanics, not getting into my backside as well as normal, and I think that led to velocity being down and the fastball — four-seam and two-seam — being a little bit flatter than usual,” Wilson said. “Yeah, I was searching for it pretty much all game, but it’s just one of those days where we couldn’t find it.”

On the other side of things, the offense was near impotent again. Wilson actually secured one of the team’s two RBIs, with a sacrifice bunt scoring Wilmer Difo in the second. Center fielder Bryan Reynolds had the other, poking a sacrifice fly to center that scored Kevin Newman, who had tripled.

After that, through the final six innings, the Pirates went down 1-2-3 in all but the eighth inning. Infielder Hoy Park and Newman walked and singled in the eighth inning, respectively, but nothing came of the mini-rally.

That’s a recipe for a loss, and the Pirates have found different recipes 13 times this season, with the opportunity to secure a sweep. But all of those recipes result in the same thing: a loss. The Pirates have just six series remaining this season to avoid making the wrong kind of history.