DETROIT -- Cooper Criswell, backed by a sharp five-pitch arsenal that included a new slider, was absolutely cruising on Sunday afternoon at Comerica Park.

He retired the first 12 Tigers he faced, needing just 52 pitches to get there.

Perfect as he was, things have been imperfect for several weeks for the Red Sox, and the downward spiral continued in a 4-1 loss to the Tigers that led to one main question: Why did Red Sox manager Alex Cora take Criswell out and bring on lefty Rich Hill to start the bottom of the fifth inning?

“That’s the way we drew it up,” said Cora. “They had a bunch of lefties, he gave us enough and we went to Rich in that situation. We had a big pocket of lefties and just, the righty burnt us.”

Before the burn of Spencer Torkelson’s go-ahead two-run homer on a hanging curveball by Hill came the 12-pitch walk to lead off the inning by Kerry Carpenter. Making it sting worse is that Hill was ahead in the count 0-2.

The lane that Cora saw with all the lefties got murkier once Carpenter fought his way on to become Detroit’s first baserunner of the day.

“Getting ahead the way that I did and then obviously the walk, that was just terrible,” Hill said. “The poorly executed curveball there to Torkelson. So you know, this loss is on me. I’ve just got to do better, that’s it. At the end of the day, make better pitches and put guys away when you’re ahead like that.”

The defeat dropped the 70-67 Red Sox 4 1/2 games back in the AL Wild Card standings, as they trail the Twins and the Royals by that same deficit.

Scoreboard watching isn’t going to be constructive for Boston unless it can start stringing wins together. The next chance to do so will be the start of a three-game series in New York against the Mets on Monday night.

Did Cora give any thought to flipping the pitching script once Criswell came out of the gate on such a roll?

“No, not really,” said Cora. “He threw the ball [well] and we felt like Carpenter has been good against righties. We had the lead. So we went to the lefty.”

It is part of mixing and matching in this era of baseball, and it’s a good feeling for a manager when it works.

Then, there are days like Sunday.

“We talked about it before the game,” said Cora. “If we find a lane, and it feels like it makes sense to us … if it was four [for Criswell], Rich goes two. And then after that, we go to the righties. Sometimes it works, sometimes it doesn't, and today we got burnt.”

Was the plan something Cora went over with Criswell before the game?

“Honestly, from my end, they know that I'll take the ball whenever we feel like that's enough,” said Cora. “And he understood that.”

Criswell, Boston’s No. 5 starter, stood by his manager.

“Obviously, you want to be out there, but I'm not gonna say anything against [Cora],” said Criswell. “Obviously, I would like to be out there, but when we scored that run [in the top of the fifth], he told me that I was done for the day, so just kind of shook his hand and got a hug from him.”

On the plus side, Criswell continued a week-long run in which Boston’s starters have been brilliant.

“I had four to five pitches working, and I felt like that’s the first time I’ve had that in several outings,” Criswell said. “That was nice, for sure.”

With the Red Sox struggling mightily at the plate over the last 10 games (.205/.246/.357 while scoring 2.9 runs per game), pitching decisions like the one Cora made on Sunday are more magnified.

And the bats couldn’t get anything going after Hill’s mishap in the fifth. Zack Kelly gave up a two-run homer to Riley Greene in the sixth, spreading the lead to three runs.

“Right now, there’s not much going on,” said Cora. “It’s been going on for a while. We’ve just got to regroup, reassess and go from there [on Monday]. We're not even [hitting the ball hard]. We haven’t done that in a while. We have to get back to dominating the strike zone, hit pitches in the zone, hit them hard, and when you start doing that, good things are going to happen.”