Selig said Wednesday that the seven-member panel appointed this year has worked independently and came up with the list. The panel is headed by Bill DeWitt Jr., chairman of the St. Louis Cardinals.
Owners meet in Baltimore next week. Selig is retiring in January.
There have been several reports that the three finalists are Rob Manfred, MLB's chief operating officer; Tim Brosnan, MLB's executive vice president for business and Tom Werner, chairman of the Boston Red Sox.
Asked about those names, Selig said "the list is accurate."
A candidate has to be approved by 23 of the 30 teams to be elected.
Miami Marlins right-hander Jarred Cosart has been scratched from his next start because of a strained oblique muscle.
Rookie left-hander Brian Flynn will start in Cosart's place Thursday night at Pittsburgh.
The Marlins got Cosart last week in a trade with Houston. He made his Miami debut Friday and took the loss against Cincinnati, giving up four runs in 51/3 innings. He was 9-7 with a 4.41 earned-run average with the Astros.
Flynn was recalled from triple-A New Orleans on Tuesday when right-hander
The Chicago Cubs designated outfielder Nate Schierholtz for assignment.
Schierholtz hit a career-high 21 home runs for the Cubs last season but this year was hitting .192 with six home runs and 33 runs batted in.
The Colorado Rockies put left-hander Brett Anderson on the 15-day disabled list.