Chicago White Sox rookie Yermin Mercedes wrote in an Instagram post on Wednesday night that he is "stepping aside" from baseball indefinitely while also apologizing to the team for not "accepting some of their decisions."

The post was accompanied with a picture of the words "it's over."

"I want to apologize to all those who I inadvertently offended as a consequence of my immaturity like members of the radio, television, and press," Mercedes wrote in his post. "To all the team's members where I was involved with, I'm sorry for failing as a human being and for not accepting some of their decisions. I'm stepping aside from baseball indefinitely."

It's unclear what decisions Mercedes was referencing in his post.

Earlier Wednesday, on his Instagram story, Mercedes had posted "El Retiro" -- or retirement -- with a thinking emoji.

Mercedes, 28, earned AL Player of the Week to open the season and hit .415 with five homers and 16 RBIs in 22 games in April, but he struggled after that. His batting average dropped to .271 before he was demoted to Triple-A Charlotte at the beginning of July.

The White Sox were seemingly caught off guard about Mercedes' intentions Wednesday night.

"The White Sox are aware of tonight's Instagram post by Yermín Mercedes, who is currently on the active roster of our Class AAA team in Charlotte, NC," the team said in a statement. "At this point in time, the White Sox have not received any official notification from Yermín concerning his future plans."

Mercedes wore his emotions on his sleeve, playing with swagger as an older rookie, but he was the subject of controversy in May when White Sox manager Tony La Russa criticized him for swinging at a 3-0 pitch late in a blowout victory over the Minnesota Twins. Mercedes responded that he wasn't going to change as he endeared himself to White Sox fans after making the team when left fielder Eloy Jimenez got injured in spring training. A local eatery even named a hamburger named after him: the "Yerminator."

Mercedes ran into other issues besides swinging at a 3-0 pitch. He was benched in an early May game for arriving to the ballpark late, and he expressed disappointment after being sent down to the minors.