CHICAGO – The unpredictability of concussions is nearly as worrisome as the injury itself.

They have drawn increased scrutiny in Major League Baseball, and for the first time since a new disabled list was implemented in 2011 for players suffering from concussions, the Sox are dealing with the uncertainty of head injuries. First baseman Paul Konerko landed on the seven-day DL Friday with a mild concussion, and the date of his return remains unclear.

All it took was a glancing blow to Konerko’s right temple. As Konerko made a play at first during the seventh inning Tuesday against the Royals, Jarrod Dyson’s elbow connected with his head. Although Konerko remained in the game, he did not play in Wednesday’s series finale.

Konerko will be eligible to come off the DL Friday at Kansas City. But manager Robin Ventura did not sound optimistic about Konerko’s chances of being ready by then. Because his only job now is to rest, Konerko will not join the Sox on the first leg of their road trip to Toronto.

“I think anything's possible, but again we're trying to figure it out as he's coming in and talk to him,” Ventura said. “I guess it's more how he sleeps. I think he had problems sleeping the first night, and even going from there he's going to have to start moving around and running again. There's going to be little steps he's going to have to take to get cleared. I don't think it's going to be as easy as picking seven days and thinking that's going to be it.”

Konerko, who is hitting .316 this season with 18 home runs and 54 RBI, faces a tough road to get back on the field. MLB’s concussion policy makes it difficult for players to be added or removed from the seven-day DL.

As soon as Konerko, 36, was diagnosed with a concussion – and regardless whether he was put on the special disabled list – there are checkpoints he must clear before returning to the field. Once a return-to-play form is submitted to the league’s medical director, the Sox must prove Konerko does not exhibit any concussion symptoms, including during baseball-related activities. Konerko’s ImPACT test results have to return to baseline, and the team physician also must believe it is safe for him to play.

MLB also can request additional information or documentation before clearing him.

“It's not easy to get on the list or get off the list,” Ventura said. “They're going to have to go through their channels of testing him and sending people to make sure he's all right and tests fine and going to be able to play.”

Offensively, the Sox's bench is trying to step up in his absence. Without Konerko in the lineup, Adam Dunn has assumed everyday duties at first base, and Ventura plans to mix and match in the designated hitter spot.

Even as the Sox battle to hold off the Detroit Tigers for the AL Central title, Konerko’s teammates are hoping for a quick recovery.

“Paul’s a great friend of mine – been here with him for eight years now,” catcher A.J. Pierzynski said. “You never want to see anybody get hurt, but especially up in the head with a concussion and that kind of stuff. It’s just usually bad news. Hopefully he gets well soon, and hopefully he gets back in a week.”