With a month left to go in the 2019 season — year 3 of the rebuild — the White Sox starting rotation for 2020 should be shaping up as a strength, but it’s far from firm.

An eight-run blitz by the hard-hitting Twins over two-plus innings against prized rookie right-hander Dylan Cease in the Sox’ 10-5 loss Thursday underscored that. Michael Kopech, who has made four major league starts, will be coming off Tommy John surgery. Opening Day starter Carlos Rodon will be, too, and won’t be ready till about the All-Star break at the earliest.

Reynaldo Lopez (5.08 ERA) is still looking to put his first good full season together and Cease has become more question mark than sure thing, let alone a potential top of the rotation starter as advertised while he was soaring to Minor League Pitcher of the Year status from MLB Pipeline in 2018.

The only almost-sure good thing right now is All-Star right-hander Lucas Giolito. Adding a free agent? The Sox will certainly do that (veteran righty Ivan Nova’s contract is up after this season) but no one expects them to seriously pursue the best and likely priciest of the lot, right-hander Gerrit Cole.

With a 100-mph fastball — which Cease flashed despite the awful results Thursday — and a curveball that tumbles from top to bottom with the best pitchers in the game, Cease has top of the rotation stuff but only spurts of good results to show for it.

Perhaps it’s as simple as not tipping pitches to hitters, which the Sox suspected was happening, and not for the first time.

“When you see a hitter spin on a particular pitch, when you have the type of velocity he has and you see them spin on a breaking ball, it kind of makes you ponder, ‘Maybe they have something,’ ” manager Rick Renteria said.

“We’ll look at video and move on from there,” catcher James McCann said. “Maybe that’s the positive take from today. ‘OK, we’re telling them what was coming.’ We make the adjustment and see how next time it goes.”

Getting that cleared up before next season would be a good thing. Next to Kopech, Cease, 23, is the Sox’ top pitching prospect, and he was rocked for 10 hits, the knockout blows coming on home runs by Jake Cave and C.J. Cron to open the third inning, giving the Twins an 8-0 lead.

In 11 starts, Cease has given up 13 homers with at least one in every game. The big inning has been has bugaboo but often followed with a run of success. On Thursday, the Twins scored multiple runs in the first, second and third.

“It’s possible [I was tipping],” Cease said.

“The stuff was there. I’ll have to go back and look at video, but I guarantee if I execute pitches better, it’s a better result.”

The Twins certainly looked like they knew what was coming. Cease allowed five consecutive singles to open the game and four runs in the first inning on six hits. He gave up two runs on two singles and a walk in the second to give the Twins a 6-0 lead.

Cease threw 61 pitches, 40 for strikes. He uncorked two high pitches on his arm side well out of the strike zone, one officially a wild pitch, and one prompting Sox training staff and manager Rick Renteria to visit the mound to make sure he was OK after a slip.

Cease (3-7) saw his ERA climb to 6.92.

“At some point you need to get a little upset, you know, ‘I’m getting hit,’ “ Renteria said. “Those things occur and then you go, ‘OK, I’ve got to do something about this.’ “