Those four were among the top five in Cleveland's lineup and combined for only one hit in a 6-2 loss to the Detroit Tigers.
"I'm disappointed because some of these guys don't seem to be making much progress getting out of these slumps," Acta said. "Some of them have been going for three months, and they are way too talented to be struggling for this long.
"It's not good."
With Sizemore and Co. struggling and slugger Travis Hafner on the disabled list, the Indians have scored two or fewer runs in 10 of their last 13 games and have been shut out four times during the woeful stretch.
The lack of offense has led to Cleveland collapsing with 16 losses in its last 22 games since sitting on a seven-game lead in the AL Central on May 23.
The Indians will make the short trip home to play Pittsburgh and Colorado, two teams hovering around the .500 mark, and Acta is hoping for a turnaround.
"We must have a good homestand," Acta said. "If we want to snap out of this, we must play well at home."
Detroit left the Motor City on a roll, winning two of three against Cleveland and 13 of their last 18 games overall to move atop the division standings.
"We've got a little something going," manager Jim Leyland said. "But it's such a long grind. I don't get carried away."
Max Scherzer (9-3) gave up two runs — both in the first — and four hits over 5 2-3 innings.
"That first inning, he made some mistakes and they hit the ball hard," Avila said. "After that, he settled in. A lot of guys like with him with overpowering stuff, you either get them early or they shut you down."
Talbot (2-4) allowed six runs on nine hits and two walks over four innings.
"This was just one of those days where I had nothing to offer," he said. "I felt pretty good in the bullpen, but I got to the game mound, and it all went away."
Frank Herrmann pitched three innings and Joe Smith threw one without giving up a run, but Cleveland couldn't come back offensively.
The Indians got off to good start with two runs in the first inning, getting some help from Raburn's error.
Michael Brantley hit a two-out triple and scored on Raburn's errant relay throw. Asdrubal Cabrera followed with a double and scored on Choo's triple to put Cleveland up 2-0.
As disappointed as Acta is, he's not ready to panic about the Indians' place in the standings.
"I'm never going to say things are critical with three-and-a-half months left in the season," he said.
Notes: Asdrubal Cabrera made a highlight-worthy, inning-ending double play in the first, catching a liner and making a slick, behind-the-back toss to second baseman Cord Phelps. ... The Indians are 2-10 at Comerica Park since the start of last season. ... Cleveland lost for just the fourth time in 19 games when it score in the first inning.