– Jim Bouton’s fantastic baseball journal “Ball Four” was released in 1970 and changed sports books and sports journalism forever. This included a passage on Harmon Killebrew, the most feared slugger in the American League at the time the book was published.

Bouton wrote that most players referred to Killebrew as “Brew,” but that Fritz Peterson, a lefthander for the Yankees, always referred to him as the Fat Kid.

“I’d say, ‘How’d you do, Fritz?’ ” Bouton wrote. “And he’d answer, ‘The Fat Kid hit a double with the bases loaded.’ ”

This was offered with considerable reverence — a suggestion from a rival pitcher that while Harmon might have had the frame of the last kid taken in a pickup game, he was also the last hitter a pitcher wanted to face when an extra-base hit was going to beat him.

Five decades later, there is a hitter with the power and bat speed to offer the best reminder yet of Killebrew in a Twins uniform, but if anyone had the audacity to call him “the fat kid” this spring, it would not be as a show of respect.

First of all, Miguel Sano is not fat (nor was Killebrew). He is 6-foot-4 and massive across his shoulders and in his legs.

Miguel Sano has “done OK” this spring, manager Paul Molitor said, but that’s probably not what the Twins were hoping for.

What all those muscles are not is taut. He is heavier this spring than last. He is at 270-plus when the Twins were hoping to have him at 260-minus as they go forward with the plan to play him in right field.

The No. 1 flaw for the Twins in their Sano strategy was not the idea of putting him in a corner outfield position. The No. 1 flaw was making no impact with their pleas to Sano to get in prime condition.

He’s never going to get below the 260s. And he’s always going to be able to hit. But right now, he’s a 22-year-old kid rather than a 22-year-old professional ready to put in the work that would allow him to be an All-Star in his first full season.

The Twins are uncomfortable talking about Sano’s size. They have no interest in sharing specifics. General Manager Terry Ryan was seen at the minor league fields earlier this month having what seemed like a heart-to-heart talk with Sano. Paul Molitor has had him in the manager’s office on occasion.

“He gives me the big smile and says, ‘Don’t worry, Papi; it’s good,’ ” Molitor said.

Molitor was asked about his level of concern with Sano’s “physical condition” in an interview early Saturday morning. As always, Molitor contemplated his answer and then said:

“He’s a young man who has a lot of things going on in his life. He has family and friends pulling on him, and a new agency [Roc Nation Sports] that’s trying to do things with him.

“We’re trying to keep his priorities straight as best we can. When I’ve watched him work on the field, it’s been good. Away from here …

“We’re trying to get him focused on the fact that once you do things to reach the big leagues, you have to do the things to remain successful and stay here.”

Molitor paused and summarized Sano’s spring with, “He’s done OK.”

I would guess “OK” would be at the top of the scale of what anyone with the Twins could say about Sano’s effort to get ready for his first full season and the transition to right field.

I was here for 2½ weeks in early February and was at the ballpark most days to do a radio show. Sano was doing low-key drills with early arrivers for a couple of days, and then he was gone.

The word was he had gone to New York for a weekend for a well-paid autograph gig, and he would be back early the next week. He wound up going back to the Dominican Republic and stayed for two weeks, until camp was ready to open.

Big deal?

No. It’s merely that I heard a Twins official say in an MLB Network interview that Sano was in Fort Myers, working every day on right field skills, while he was in the Dominican hanging with buddies.

“He’s a big man and we have him playing a new position, so the challenge for Miguel and for us will be to keep him on the field,” Molitor said. “He’s important. You don’t want to single out one guy as the most important to success, but it would be a tough bat to replace.”

Tough, and then some.

The Twins’ plan to move to Sano to right field is not as unfortunate as Sano’s modest effort to get ready for it in this offseason.

He’s going to mature with his mental approach and become an everyday force in the lineup, whether it’s in right field, on an infield corner or as designated hitter. For the Twins, it’s a matter of when.

Right now, Miguel Sano is far from the long-awaited, second coming of the Fat Kid. He’s simply the Big Kid, until he begins to take his shot at greatness more seriously.