Speaking about the lineup that finished Game 4 of Miami's series against the Chicago Bulls, Spoelstra didn't expect to see Miller or Udonis Haslem, who was slow in recovering from November foot surgery, play together on the court this season.
"Six weeks ago, my training staff was tempering my expectations that it wouldn't even happen that [Udonis Haslem] would come back so I wasn't even planning on [him]," Spoelstra said. "And a month ago, Mike [Miller] had just ruptured his ligament in his left thumb so I didn't know how productive he would be in the playoffs."
Spoelstra had previously said that Miller's thumb was badly injured, but he never revealed any specifics. It is unknown precisely when the rupture occurred but Miller was visibly bothered by his left thumb during Game 1 of the Heat's first-round series against the Philadelphia 76ers.
After playing just six minutes total in the first two games of the first-round, Miller sat out the rest of the series. He received about two weeks off before playing in the Eastern Conference semifinals against the Boston Celtics.
Entering Tuesday's Game 4, Miller had struggled in the playoffs, shooting just 20 percent from the floor, including 1-for-10 on 3-pointers. He recorded 12 points and nine rebounds in 26 minutes in Game 4, which were all playoff-highs for the 31-year-old this season.
Miller already missed nearly three months of the regular season due to a similar injury to his right thumb, which required surgery in October. He made his Heat debut on Dec. 20 against the Dallas Mavericks.
Miller issues also extend off the court.
His wife gave birth to a baby girl last Thursday in a South Florida hospital, but the newborn daughter has remained in the intensive care unit with an undisclosed health issue. Miller left with the team on Wednesday to travel to Chicago.
Tom Haberstroh is a writer for ESPN Insider.