- Bats Left, Throws Left
- Height 6' 4", Weight 204 lb.
Polanco signed with the Pirates in March 2009; the scouts were Ellis Pena and Rene Gayo. That summer, he hit .267/.370/.357 with 34 runs, 6 triples and 33 walks in 63 games for the DSL Pirates. He was awful at the plate with the 2010 GCL Pirates (.202/.245/.287), though he did steal 19 bases in 21 tries. He was 4th in the Gulf Coast League in stolen bases, trailing Eddie Rosario, Matt Lipka and Junior Sosa. 2011 showed little progress as he hit .237/.333/.361 with 18 steals in 18 tries for the GCL Pirates and was 1 for 10 for the State College Spikes. He tied for 7th in the GCL in swipes.
Gregory's stock soared in 2012. He produced at a .325/.388/.522 clip with 16 home runs, 84 runs, 85 RBI, 40 steals in 55 tries and 12 outfield assists to 3 errors for the West Virginia Power before an ankle strain cut his season short at 116 games. He reinjured the ankle during drills with the Navy SEALs, a move much criticized by journalist Dejan Kovacevic; the Pirates cut the drills after the season amidst the protests. Polanco finished among the South Atlantic League leaders in average (2nd, .010 behind Brant Keys), slugging percentage (5th), runs (tied for 4th with Garin Cecchini), triples (6, tied for 6th), home runs (tied for 9th), RBI (3rd behind Zach Johnson and Matt Skole), total bases (228, 5th between Austin Barnes and Maikel Franco), steals (tied for 4th with Jesus Galindo) and OPS (3rd behind Skole and Harold Riggins). He joined Keys and Keury De La Cruz as the All-Star outfielders and won the league's award of Most Outstanding Prospect. Among Pirate farmhands, he had the most steals, tied Jeff Clement, Alen Hanson and Jose Ozuna for second in home runs (behind Willy Garcia), was second to Alex Dickerson in RBI and was second to Brock Holt in batting average. Baseball America named him the league's #3 prospect behind Jose Fernandez and Trevor Story. They also put him down as the #51 prospect in the minors, third in the Pirate chain behind Gerrit Cole and Jameson Taillon. They also rated him as the best hitter for average, best athlete and best defensive outfielder among Pittsburgh minor leaguers. The Pirates named him their Minor League Player of the Year.
Polanco was healthy to open 2013 with the Bradenton Marauders and batted .312/.362/.472 with 24 steals and 6 homers in 57 games to earn a promotion to the AA Altoona Curve. He was picked for the World team in the 2013 Futures Game. Starting in center field and hitting 7th, he popped out in the second against Taijuan Walker and drew a walk from Anthony Ranaudo in the 4th. Galindo replaced him in center in the World's 4-2 loss. He played 127 games with three teams that season, spending time with the AA Altoona Curve and AAA Indianapolis Indians for two games in addition to Bradenton. He hit .285 with 12 homers and 71 RBIs.
He began the 2014 season in AAA with Indianapolis, amid speculation about how long it would be before he was a starter in Pittsburgh. He hit .347/.405/.540 in 62 games to show he was ready for the big stage. He made his debut with the Pirates on June 10th, when he went 1 for 5 while playing right field against the Chicago Cubs. On June 13th, he hit his first career homer in dramatic circumstances when he connected for 2 runs in the 13th inning against Mike Dunn of the Miami Marlins to give the Pirates an 8-6 win. He showed the extent of his talent by going 5 for 7 with 3 runs and 2 RBIs that game, giving him a hit in his first four major league games. His strong start prompted questions about why it had taken the Pirates so long to bring him up, when it was clear even in spring training that he was better than any other outfielder the Pirates had, apart from Andrew McCutchen. With a weakened offense, the Pirates had fallen back in the playoff race, all in order to save a little money by delaying Polanco's eligibility for arbitration by a year, running the risk on missing out on some lucrative postseason games. He eventually extended his hitting streak from the start of his career to 11 games, during which he hit .365, but he soon cooled down. By the end of July, he had fallen to .247 and on August 25th, the Pirates, still in a tough race for a postseason slot, bit the bullet and sent him down to AAA to regain his hitting stroke for the September stretch run. By then, he was down to .241 with 6 homers and 30 RBI in 64 games, and was 1 for his last 30 at-bats. He finished the year at .235 in 89 games.
Polanco took a big step forward in 2015, as the Pirates had a great year, finishing with the second best record overall in the majors. In 153 games, he hit .256 with 9 homers and 52 RBIs while scoring 83 runs and stealing 27 bases. Combined with the production of McCutchen in center and Starling Marte in left, it gave the Pirates arguably the best outfield in the majors that year. However, the season went for naught when the Pirates were shut out by the Chicago Cubs in the Wild Card Game with Gregory going 0-for-4. In 2016, he continued tom improve, hitting .258 in 144 games, but with 34 doubles and 22 homers, leading to 79 runs scored and 86 RBIs as he continued to evolve into a run producer. The Pirates missed the postseason that year, though, and after the season, they shuffled their outfield, moving McCutchen to right and Marte to center, with Polanco sliding form right field to left in 2017.
On July 14, 2018, Polanco and Starling Marte became just the third pair of teammates to hit back-to-back homers in both games of a doubleheader and the first in 50 years since Reggie Jackson and Sal Bando did it July 7, 1968. The only other previous occurrence was Frank Thomas and Dick Groat on July 7, 1957. On September 7th, he injured his knee when he slid awkwardly into second base in a game against the Miami Marlins; the resulting bone bruise brought his season to an early end. In 130 games, he had hit .254 with a career-high 23 homers and 81 RBIs, good for an excellent OPS+ of 128. In 2019, with the Pirates having a tough season, he missed a good portion of the year as his recovery from off-season shoulder surgery was slower than anticipated. He was activated at the end of April, but returned to the injured list two months later and never returned, playing his last game on June 16th. In 42 games, he hit .242 with 6 homers and 17 RBIs. Health woes continued in 2020, as he missed a scheduled intrasquad game on July 15th and it was announced a couple of days later that it was due to a positive COVID-19 test. This time, though, he managed to play 50 of the team's 60 games, although he had a dreadful season with the bat, hitting just .153. He actually played more games and had more at-bats then in 2019, and his power numbers were similar - 6 doubles, 7 homers and 22 RBIs, but his complete inability to hit for average resulted in an OPS+ of just 45.
Following his poor 2020 season, he joined the Leones del Escogido in the Dominican League but after 21 games of hitting .197, it was announced that he had a small, non-displaced fracture in his right wrist and would no longer play that season in order to rest and be ready for spring training. It turned out that it was not a fracture and that he was fully healthy in spring training in 2021.
- 20-Home Run Seasons: 2 (2016 & 2018)