ST. LOUIS — Before this miserable week for the Royals, it had been 13 years since a team had swept the I-70 Series in one season.

But the Cardinals used a familiar script, albeit one that didn’t involve a stray animal, and beat the Royals 8-6 at Busch Stadium on Thursday night, completing a four-game series sweep. Since Monday, the Royals have gone from holding the second wild-card spot to trailing the Mariners, Rays and now the Twins.

And the Royals’ script this week has, unfortunately, featured an overworked bullpen. Only one starter managed to pitch as many as six innings, putting a strain on the relievers, who allowed 19 runs in 16 innings in the four games.

“Kel (Herrera) hasn’t pitched much, because we haven’t been in a situation where he can pitch,” Yost said. “It’s kind of a bullpen slump, a little bit, but it’s a good bullpen. They’ll fight their way through it.”

One of the turning points Thursday came on an 0-2 pitch from Royals starter Jason Hammel to Cardinals shortstop Paul DeJong.

The Royals led 3-0 in the sixth inning, but Hammel’s pitch plunked DeJong and St. Louis center fielder Dexter Fowler followed with an RBI double.

Yost had hoped to squeeze out six innings from his starter, but a pair of errors helped elevate Hammel’s pitch count and then came the hit batsman.

“That’s the mistake that I’d want back,” Hammel said. “It was more just pitch selection. On 0-2 there, and trying not to get myself in trouble, we went with the fourth-best pitch, probably wasn’t one that I was overly committed to. I was thinking probably sinker or slider there, and I didn’t really throw it with conviction.

“I ended up putting a runner on, and Dexter battled me pretty well.”

Yost called on Peter Moylan to face Cardinals catcher Yadier Molina again, one night after Molina’s grand slam off Moylan proved to be the key blow in St. Louis’ win.

Molina won Round 2, too, spanking a single to left that put runners on the corners with no outs. Moylan appeared to help himself out when he snared a ball off the bat of the next hitter, Jose Martinez. However, Moylan threw the ball into center field and Fowler trotted home as Molina scooted to third.

Yost summoned left-hander Mike Minor, but Kolten Wong lifted a fly to left field that scored Molina. However, Minor got out of the inning and kept the score at 3-3.

But the Cardinals took the lead the next inning thanks to another grand slam.

On Wednesday night, a field-invading cat preceded a St. Louis slam. On Thursday, it was merely a result of a terrible outing from Royals relief pitcher Neftali Feliz.

Matt Carpenter opened the Cardinals’ half of the seventh with a single against Minor. Yost brought in Feliz, who faced four batters and failed to record an out.

Carpenter moved to third when Tommy Pham singled to right, and Pham stole second. DeJong drew a walk to load the bases, and Fowler turned on a 94 mph fastball, sending the ball into the Cardinals’ bullpen in right field, giving St. Louis a 7-3 advantage.

In the top of the eighth inning, Royals pinch hitter Brandon Moss stepped to the plate with the bases loaded and one out. Moss had been 0 for 7 as a pinch hitter, but he crushed Seung Hwan Oh’s pitch, hitting it off the wall in right-center for a two-run double.

“It missed by about 6 inches,” Yost lamented. “It hit right on that pad.”

Whit Merrifield’s sacrifice fly to left got the Royals within one, but Trevor Rosenthal entered for St. Louis and got Lorenzo Cain on a long fly down the right-field line.

The Cardinals pulled a run back against Royals’ reliever Joakim Soria in the bottom of the eighth.

While the Royals bullpen had a troubling week, it wasn’t all to blame for Thursday’s loss. Mike Moustakas and Alcides Escobar made errors that prolonged innings, and the Royals scored a run in the second inning, but didn’t add to that tally despite having the bases loaded with no outs.

And despite a four-hit game, Cain was caught straying off second base to end the third inning when he lost track of the count.

“When I looked up, I thought it said 0-2 on the board,” Cain said. “So when I looked up, I saw 0-2, and when he swung, I thought it was strike three. And then that’s when I started walking. I was taking my helmet off.

“That’s my fault. I got to know the count there.”

The Royals’ freaky, streaky season continues. They’ve had winning and losing streaks of nine games, but losing four straight to the state rivals hurts more than the Royals’ pride because they are in a multi-team race for the playoffs.

Cain was asked if the Royals have another good streak in them.

“I hope so,” Cain said. “As a team, we’ve definitely been swinging the bats a lot better. But we’ve just been falling a little short as of late. As a team, we just got to be clicking at the same time. For them to take four games from us, that definitely hurts. We’ve got to bounce back.”