CHICAGO — Even Bartolo Colon, the Mets’ ageless wonder, is not exempt from the ravages of time. Perhaps that was the cleanest explanation for what has been a swift downturn.

Colon, 43, got roughed up Wednesday in a 6-2 loss to the Cubs. The righty gave up two mammoth homers to slugger Anthony Rizzo, who knocked in three runs.

Colon (8-5) allowed six runs and eight hits in 4 1⁄3 innings. In his last three starts, totaling 14 2⁄3 innings, he has posted a 7.37 ERA, surrendering 22 hits and five homers. His ERA has jumped from 2.87 to 3.48.

“They prepared themselves mentally for me and I paid for the consequences,” Colon said through a translator.

Following the game, Colon shot down the notion of pitching through fatigue, and manager Terry Collins painted the tough start as an isolated incident.

“That’s a pretty good indication,” Collins said, noting that the typically precise Colon walked two batters in the first inning. “There’s days I don’t see Bartolo throw 15 balls in five innings, let alone in one inning. It’s certainly uncharacteristic. But you’re going to have blips like that every once in a while.”

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Collins couldn’t dismiss the possibility that age could be showing. Still, he noted a reality that faces the Mets as they slog through the start of the second half. Even if Colon needs extra days of rest to catch his breath, the Mets and their banged-up rotation can’t afford such a luxury.

“If he was 53, he’d be out there,” Collins said.

Starting only his second game since the All-Star break, Wilmer Flores hit a two-run shot, his seventh homer of July. But the big swing came only after Kyle Hendricks (9-6) had wrapped up another stellar afternoon. The Cubs righty tossed 6 1/3 scoreless innings, lowering his ERA to 2.27, third in the big leagues. With a deceptive combination of his two-seam fastball and an effective changeup, Hendricks continued his dominance at Wrigley Field.

“He doesn’t give you many pitches to hit,” Flores said.

At Wrigley Hendricks owns a 1.36 ERA, second only to the Dodgers’ Clayton Kershaw (1.31) for the best at home this season.

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Hendricks also had the added benefit of facing a Mets lineup missing three regulars. Collins rested Yoenis Cespedes and his sore right quadriceps. Second baseman Neil Walker and shortstop Asdrubal Cabrera also got the day off, with Collins saying that both had looked fatigued.

Filling in at second, Kelly Johnson lived up to his reputation for producing despite sporadic playing time, going 4-for-4. The output equaled a career high, though it wasn’t nearly enough for the Mets. They were 2-for-9 with runners in scoring position, although neither hit knocked in a run. Slow-footed James Loney was thrown out trying to score on Johnson’s single in the fourth.

The third-place Mets dropped two of three to the Cubs, although they won the season series, 5-2. After today’s off day, they begin a critical three-game set against the Marlins, who have pulled into second place.

The Mets (50-44) have fallen 6 1⁄2 games back of the NL-East leading Nationals and one behind the Marlins (51-43), who are eight games over the .500 mark.

“It’s not surprising,” said Flores, who is expected to start against Adam Conley, the Marlins lefty in line to start Friday night. “They have a good team.”

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The challenge becomes even more difficult Saturday, when Marlins ace Jose Fernandez — 11-4, 2.53 and “almost unbeatable at home,” as Collins said — matches up against Jacob deGrom (6-4, 2.38).

“We’ve got to go win two,” Collins said. “We’ve got to come out of there and go make up some ground. There’s no doubt it’s going to be a big weekend for us.”