PITTSBURGH — Before the A’s second game at Fenway Park this week, three infielders joined Jurickson Profar for early work just to give the struggling second baseman a boost. Matt Chapman, Marcus Semien and Chad Pinder all accompanied him to the field as moral support.

“They just wanted to be here with him because they know he feels bad about it,” third-base coach Matt Williams said. “That’s a testament to them as teammates. You just don’t find that today. That’s a special thing.”

Semien, in particular, gets what Profar is enduring. Profar’s seven errors are the most among big-league second basemen; four years ago, Semien made 16 errors in the first month and a half of the season and was searching for answers, too. Since working with then-infield coach Ron Washington the rest of that season and the next, Semien has turned into one of the top all-around shortstops in the game.

“I feel like I have more input I can give now, because I’ve been in a low place and now I feel like I’m doing better,” Semien said. “So I’m trying to help Jurickson out with what worked for me. But everyone’s different. Something I say might not work for him, but at least we talk about it and figure it out.”

Profar, who politely declined comment for this story, was benched the final two days at Boston and spent a great deal of time working with Williams and first-base coach Al Pedrique before the games. Pedrique pointed out that Profar hasn’t played full-time at second base — he had played more at shortstop and at third in the majors before this season.

“I think it’s the lack of playing time at second base,” Pedrique said. “You definitely have to make an adjustment: footwork, how hard the ball is hit, how much time you have because you’re closer to first base, and the arm angle is different. Right now, we’re just keeping it simple: get ready, hands out front and step toward the target. He needs to move his feet toward first and let it go. Don’t think about it.

“The mistake we make as infielders sometimes is we know we have too much time, we relax too much and then we just flip it to first base instead of letting it go. In that situation, he slows down, his body goes up and anytime you do that, most of the time the throws are going to go straight down to the dirt.”

Based on Pedrique’s assessment, the throwing issue is not the yips. But the fact that Profar’s biggest trouble has been on short tosses has led to a belief among scouts that the problem might be more in his head than it is mechanical. (A’s designated hitter Khris Davis has spoken about his own trouble throwing; he calls it “the Creature.”)

“I haven’t played with many guys with the yips, but that can destroy a player,” one longtime AL scout said. “If Profar is not hitting and he’s having trouble throwing, if he’s dealing with all of that, I feel bad for the guy.

“He was a high-profile guy and he’s always had ability, but he’s just erratic defensively and you accept it if he’s batting .300. If he’s not producing offensively, he’s a liability for pitchers. Some guys, when the bat goes south, they’ll make boneheaded plays defensively, and you’ve got to sit them to get them straightened out.”

Such a dynamic — troubles at the plate turn into troubles afield and vice versa — isn’t uncommon, especially among younger players. Profar is still only 26. He’s batting .165 going into Friday’s series opener at Pittsburgh.

“There’s a lot of mental stuff that’s going on, especially when the game isn’t going your way,” Pedrique said. “You’re having a long week or a long month, and you don’t want to do that but sometimes you take it to your defense.”

Williams pointed out that Profar’s throwing issues simply might derive from the fact that he had right shoulder surgery in 2015 and needed a long recovery process.

“Jurickson essentially had to relearn the slot he throws from,” Williams said. “Playing on the left side of the diamond, you have to make a forceful throw to get it across there, and he doesn’t have any problem with that. It’s the touch throw he’s having an issue with.”

That means lots of early work and drills for Profar as he tries to find that arm slot and refine his footwork.

The main thing, Williams said, is ensuring Profar can react naturally.

“You can imagine the ball being hit and thinking, ‘Oh no, I don’t know where my slot’s at,’ or, ‘I feel uncomfortable about this throw,’ and that’s a bad spot to be in,” Williams said. “We’re just trying to eliminate all of that to find the comfort level and let Jurickson play.”

It’s only a month into the season, Williams noted, a small sample size, and Profar is adjusting to a new organization as well as a different position.

“The mechanics of it all, we’ll figure it out,” he said. “I think his teammates just want him to relax and enjoy it. When you get in a space like this, it’s very easy to lose sleep at night and worry. So they’re trying everything they can, and we’re trying everything we can, to just allow him to feel comfortable, and when he does, it could be really special.”

Susan Slusser is a San Francisco Chronicle staff writer. Email: sslusser@sfchronicle.com Twitter: @susanslusser