The Indians activated the designated hitter Friday and hope the slugger is healthy enough to put some sting into an offense that went dormant while he was sidelined with a strained right oblique muscle. Acta listed Hafner as the cleanup hitter for the start of a three-game interleague series against Pittsburgh.
"People [fans] don't understand how one hitter affects the whole lineup, especially somebody like him in the middle," Acta said. "It was three weeks, actually a month, of an issue."
Hafner went on the disabled list May 20, retroactive to May 18. The Indians went 10-18 without him, really hitting the skids after building a seven-game lead in the AL Central by May 23. Since then, Cleveland was 6-16 -- with two of the wins by 1-0 scores -- while being shut out six times.
Hafner played two games at Double-A Akron earlier this week, going 3 for 6 before being hustled back to town.
"I woke up this morning and felt good," he said. "I wanted to come back. We were one of the best offenses in the league to start the year and hopefully we can get back to that."
Acta said he left the decision to Hafner to announce when he could play.
"He felt he was ready to go and we could use him," Acta said. "Having him in the lineup helps guys get back to their own spots and to relax. Guys try to pick up the slack instead of doing their thing. It is human nature."
Acta doesn't think Hafner will join teammates trying to do too much in order to snap the offense out of its doldrums.
"He's gotten past that point in his career," Acta said.
Acta won't push the 34-year-old, who has battled a succession of injuries the past four years, most notably a lingering right shoulder ailment that required surgery in 2008 and sidelined him for much of the last three seasons.
"He will DH tonight, not play Saturday, then be back in there Sunday," Acta said.
Hafner hit .345 with five homers and 22 RBI in 32 games before his latest injury. His clutch hitting helped Cleveland to a 26-13 start. He hit .483 (14 of 29) with runners in scoring position. In the past 14 games, Cleveland has hit only .120 (11 for 92) in that situation.
"It snowballs when you get into a slump," Acta said. "We had guys trying to hit a five-run homer.
"We had success early because everybody was contributing and we got some offense from unexpected sources. We can't afford to lose guys like Hafner, [Grady] Sizemore, [Shin-Soo] Choo and Asdrubal [Cabrera]. To win, we have to keep all those guys healthy and also play to the best of our abilities."
Even healthy, Hafner won't be in the starting lineup too long. After the series against the Pirates, the Indians play host to Colorado for three games before going on a nine-game trip to National League cities -- where the DH is not used. Acta is not happy about having Hafner relegated to a pinch-hitting role for such an extended period.
"I always like interleague play," he said. "What I don't like is having nine games in a row where I can't use Hafner."
To make room on the roster, Cleveland optioned outfielder Travis Buck to Triple-A Columbus. Buck batted .226 with two homers and eight RBIs in 29 games.