Miller was activated from the 10-day disabled list Friday after the Indians struggled mightily without the star left-hander, who had been sidelined since April 26 because of a strained left hamstring.
"That is good," manager Terry Francona said. "It sure is nice to have him back. He's healthy."
Cleveland's relievers complied a 9.50 ERA in 36 innings and the Indians went 5-9 without Miller. Five of the losses came after Cleveland was leading or tied in the eighth inning or later.
Miller admitted not being able to contribute was difficult. His absence led to several relievers having their roles changed. Roster moves due to poor performances and injuries followed.
"Those are things that stand out," Miller said. "When you lose guys who you really like and you want to be a part of the team. And guys get hurt. Those are bigger picture items."
Francona said consideration was given to have Miller make a couple of minor league rehab assignments.
"He honestly couldn't say that that would help him," Francona said. "I think he feels like facing major league hitters is really the only way. So you might see him on a little bit of a schedule the first week back, just to try to get him on a roll where we get him back into that midseason form where he can be a big weapon."
Cleveland leads the American League Central but was 18-18 going into Friday night's game against the Kansas City Royals.
Miller has pitched 10 scoreless innings and struck out 17 in 11 appearances. He grabbed the back of his leg after throwing a pitch against the Chicago Cubs on April 25 and was placed on the DL the following day.
The Indians lost valuable setup man Bryan Shaw to free agency in the offseason, and Miller's absence threw the bullpen into disarray.
"We're going to be fine as a unit," said Miller, who can be a free agent after the season. "We're going to be an important part of this team. Especially if we're going to do anything that we're trying to accomplish. The bullpen is going to be part of that."
He pointed out that the majority of the Indians' AL record 22-game winning streak last season came when he was on the DL with a knee injury, along with second baseman Jason Kipnis.
"I think I got back for Game 21 or something like that," Miller said with a laugh. "Maybe me and Kip came back and we were just scared to death it was going to be our fault."
Miller has been a key member of Cleveland's bullpen since being acquired from the New York Yankees for four prospects on July 31, 2016. He was 4-0 with three saves and a 1.55 ERA after the trade and helped the Indians reached the World Series.
He was even better last season, going 4-3 with two saves and a 1.44 ERA in 57 appearances, striking out 95 in 62 2/3 innings.
Left-hander Tyler Olson was placed on the paternity list and will be out from one to three days.