The club's designated hitter did not travel to Chicago for the weekend series with the White Sox.
Diaz was hitting .232 in 34 games for Akron. McAllister was 1-1 with a 3.96 ERA in four starts for the Indians.
Manager Manny Acta says Diaz will likely be sent back to the minors on Monday, when pitcher Josh Tomlin is expected to be activated from the 15-day DL. The right-hander, sidelined by a sore right wrist, threw a 50-pitch bullpen session Thursday and reported no pain.
Information from The Associated Press was used in this report.