Also recalled from the Indians were right-handers John Holdzkom and Casey Sadler, and lefty reliever Bobby LaFromboise.
Additionally, infielder/outfielder Chase d'Arnaud had his contract selected from Indianapolis. To make room for d'Arnaud on the 40-man roster, Michael Martinez was designated for assignment.
Locke had been optioned on Saturday, to clear space on the limited 25-man roster for infielder Brent Morel. Locke went 4-0 in August, so his "demotion" had been strictly for convenience.
Not so with Polanco. The Bucs' starting right fielder for more than two months was returned to the Minors on Aug. 24 in the throes of a 1-for-30 slump. At Indianapolis, Polanco went 4-for-26, with all four hits singles.
Sadler and d'Arnaud both have prior big league experience with the Pirates, the pitcher more recently. Sadler has appeared in five games this season, working a total of 9 1/3 innings in relief. d'Arnaud returns to the Pirates for the first time since 2012. Then exclusively a middle infielder, d'Arnaud has transitioned into the outfield, where he saw most of his Indianapolis play this season.
LaFromboise will take some of the burden off Justin Wilson, the Bucs' resident setup left-hander who has already appeared in a career-high 62 games.
"He's the third left-hander we have been looking for. He gives us another and earlier option for a left-hander," said manager Clint Hurdle.
LaFromboise, 28, was in the Mariners' Spring Training camp before being designated for assignment on March 27. He was first claimed off waivers by San Diego on April 2, then by the Bucs on Aug. 24.
LaFromboise, who made 10 appearances for the Mariners in 2013 (5.91 ERA in 10 games), spent most of this season with the Padres' Triple-A farm in El Paso, going 1-2 with three saves and an ERA of 4.75 in 58 outings.
Holdzkom, 26, was signed on June 23 out of independent ball. He posted a combined record of 3-0 with two saves, 1.95 ERA and 37 strikeouts in 22 relief appearances with Double-A Altoona and Triple-A Indianapolis.