Is Jon Lester really the “weakest link” in the Cubs’ starting rotation?

That’s what he called himself earlier this month after a brutal outing against the Athletics in which he gave up 11 runs, nine of them earned, in four innings.

The question was put back on the table Friday during a 9-3 loss to the Nationals at Wrigley Field in which Lester was hammered for six runs, all earned, and nine hits in 4⅓ innings.

This time, the 35-year-old lefty didn’t use the

actual words. He didn’t have to.

“Today sucks,” he said. “[Saturday], I’ll wake up and start a new day, or get ready for another start. But it doesn’t take the sting away from today.

“[Manager] Joe [Maddon] has always said, ‘You win hard, you lose hard.’ Losing for me is even harder than that. Sucking as a pitcher is even harder than that. It’s my job to do better, and I’m not.”

Lester has an 8.51 ERA in five starts in August. That includes the six scoreless innings he threw in Pittsburgh in his most recent outing before Friday, which he had hoped at the time signaled a return to usual form.

He likely has no more than half a dozen starts left the rest of the regular season. This is no way to approach September.

“Usually, this is the time of year where I pitch a lot better than I have been,” he said. “For whatever reason, I haven’t hit that stride. I usually have ups and downs through a season, but usually more ups than downs. Right now, it’s just continuing to go down. The old saying of ‘One step forward, two steps back’ [is] kind of what I’m doing right now. The positive is, physically, I feel fine. So I can’t blame it on that. I just have to be better.”

It was only the Cubs’ fourth loss in their last 20 games at home, but it wasn’t close to a fair fight. The soaring Nationals (71-57) made hard contact off Lester, starting with Adam Eaton’s solo homer in the first inning. Meanwhile, the Cubs (69-59) — a day after mustering only two hits in a 1-0 win over the Giants — had a single hit off starter Anibal Sanchez, who lasted 8⅓ innings in his longest outing since 2015. The Cubs didn’t score until the ninth, by which point the gap between the teams appeared larger than a couple of games in the National League standings.

After taking two of three games in Washington in May, the Cubs needed 13 tries to win another road series. The Nats, on the other hand, are 52-26 since May 24, battling the Dodgers (53-26 entering play Friday) for the best record in all of baseball in that span.

This time it was Juan Soto who led the Nats’ attack, homering among his three hits and scoring four runs. But it has been all hands on deck — all hands pounding — for a team that has scored 90 runs in its last nine games.

Second-year manager Dave Martinez, who was under fire a few months ago, must be doing a lot of things right. Maddon’s team has reached a season-high 11 games over .500 four times, only to lose its next game each time.

For the Cubs, this was the first of nine straight games — and 13 of 15 — against serious NL playoff contenders.

“I believe in our guys,” Maddon said. “We could easily just do the opposite to them [Saturday]. That’s within the realm of possibility. I believe in the power of 24 hours.”

And he believes in his big lefty.

“I’m fine with [Lester],” Maddon said. “I think he’s going to be fine. He will find a way to get himself back into the picture the right way. There’s a lot of time left, with the playoffs, etc. I believe in Jon.”

But Lester knows his rough days at the office are a serious matter.

“I think we’re getting to the point where you can’t isolate them,” he said. “They’re happening a little bit too much.”