Pittsburgh sent the 22-year-old rookie outfielder back to Triple-A Indianapolis on Monday, believing a week in the minors will help Polanco break out of his freefall.
Polanco made his major-league debut on June 10 and recorded at least one hit in his first 11 games but has slumped since the All-Star break. He is just 1 for 30 since Aug. 13, with his batting average dipping to a season-low .241.
The Pirates plan to recall Polanco when rosters expand next week provided he works his way back.
''The timing is off in his swing and I don't think the best way to spend the next week was with him sitting on the bench,'' Hurdle said. ''This will give him an opportunity to get down, get some at-bats and get out of the spotlight that is here ... so he can help this ballclub in September in a very positive fashion.''
Hurdle gave Polanco a few days off last week but it provided no immediate dividends. Polanco went 0 for 3 in a 4-3 loss to Milwaukee on Sunday.
Polanco's slump coincided with a surge from reserve outfielder Travis Snider, who is hitting .319 with six home runs and 18 RBI since the All-Star break entering Monday night's game against St. Louis.
Snider excelled as a pinch hitter before becoming a regular in the lineup over the last three weeks. Hurdle wasn't certain Polanco would benefit from serving in the same role while he tried to tinker with his swing.
''We want him to go down there and he'll get an opportunity to have four to five at-bats a night without magnification on him,'' Hurdle said. ''We want him to keep it simple, `Get your foot down early, get your barrel to the ball, hit it where it's pitched and come back Sept. 2 and help us.'''
Tabata hit .289 in 62 games with the Pirates earlier this season but has spent most of the summer in Indianapolis following Polanco's promotion.
''I know I've got to do my job, got to work more 100 percent, 200 percent,'' Tabata said. ''You know it's frustrating sometimes but if you're not strong, you're done.''
The 26-year-old Tabata - who is making $3 million this year - batted .281 with 12 RBI in 39 games in the minors before being recalled. He thrived in a similar position last fall, hitting .312 in September as the Pirates earned their first playoff berth in 21 years.
Pittsburgh also activated shortstop Clint Barmes off the 15-day disabled list and designated infielder Jayson Nix for assignment.