Davis was suspended for 25 games Sept. 12 after violating Major League Baseball's Joint Drug Prevention and Treatment Program. He sat out the final 17 games of the regular season, with the final eight games of the suspension carrying over into the postseason.
Because the Orioles swept the Tigers in the AL Division Series, five games remain on the suspension. Thus, even if he were on the roster, Davis wouldn't have been eligible to play in the ALCS until Game 6 -- if the series goes that long. Baltimore would have needed to play with a 24-man roster for the first five games to have the opportunity to use Davis in Games 6 and 7 that might not even happen.
"We're not going to play at 24 for five games," Showalter said.
Davis, who finished third in AL Most Valuable Player Award voting as a first baseman in 2013, moved to third base when a knee injury ended Manny Machado's season. Steve Pearce, who had been the O's primary left fielder, has become Baltimore's full-time first baseman.
With Davis' suspension, the Orioles have tried a host of players at the hot corner. Kelly Johnson arrived in Baltimore at the end of August in a trade with the Red Sox and has rotated in at the spot. Switch-hitter Jimmy Paredes was called up at the end of August and has seen action.
Both made it onto the ALDS roster, but have firmly slid into bench roles behind Ryan Flaherty, who is the best defender of the three.
Davis was at Oriole Park at Camden Yards for Baltimore's workout Thursday to take batting practice, but did not speak to reporters.
Davis finished the regular season with a .196 batting average and 26 home runs in 127 games.
David Wilson is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.