More specifically, MLB.com's Scott Merkin says Abreu has posterior tibial tendinitis in his left ankle:
"Jose Abreu made every effort possible to play through the ongoing pain in his left ankle for at least the past 10 days or two weeks.
"He even managed to deliver a game-winning, three-run homer Wednesday in Oakland while playing at far less than full strength.
"But watching how much Abreu's improvement, let alone his overall game, was hampered on Saturday pushed the White Sox to put their breakout star on the 15-day disabled list prior to Sunday's series finale in Houston with posterior tibial tendinitis in his left ankle.
"'It became clear to everyone who saw the game yesterday where it got to the point where he was basically playing on one leg,' general manager Rick Hahn said of Abreu.
"'That obviously wasn't going to work to get him to maximize his ability, much less him being fully healthy. We made the decision to err on the side of caution here.'"
The Chicago Tribune's Colleen Kane reveals Abreu's ankle issues date back to spring training in her May 18 report.
"Abreu has had ongoing problems with ankle soreness, dating to spring training when he sprained it, and he played his last eight games at designated hitter because of the new problem.
"(White Sox manager Robin) Ventura said he didn't think a couple of extra days rest at the outset of the issue would have prevented it.
"Abreu returned to Chicago to have his ankle examined further Sunday morning, and he will undergo another MRI so the Sox can rule out any other issues. He is expected to wear a walking boot to immobilize his ankle during the recovery.
"General manager Rich Hahn declined to give a timetable for Abreu's return, but he said it's 'reasonable' to think the problem can be resolved within the 15-day DL period."
This is precisely what Hahn told CSN Chicago's Dan Hayes.
"It would be pure speculation right now to discuss that it's something more serious. But since we do now have 15 days, we're going to take our time to exhaust the possibilities.
"I dislike speculating on return timeframes. Obviously we tried to do that with Chris (Sale), and sometimes recovery takes longer. It can take a little bit to get inflammation out or get rid of some soreness.
"But as of right now, it's reasonable to believe we'll able to resolve this thing within the 15-day period."
Abreu told Kane via an interpreter that he understands management's decision. He said,"If we have to take a break or whatever, then let it be. The most important thing is to be in the field and be healthy."
Abreu has 15 home runs and an American League-leading 42 RBIs through May 18, per ESPN Chicago. He is just one RBI behind the Miami Marlins' Giancarlo Stanton for the most in the league.
The 27-year-old Chicago first baseman became the first American League slugger to cop both Rookie of the Month and Player of the Month awards in April -- his very first month in the majors, according to the same ESPN update.