Pirates' Ben Cherington says Gregory Polanco, Mitch Keller will continue to get opportunities

May 15—Gregory Polanco leads the Pittsburgh Pirates in stolen bases with four, but that's not the reason he remains in right field and bats fifth in the order with a .202 batting average (before Friday).

Mitch Keller has the highest ERA (7.81) and WHIP (1.81) among Pirates starters, but manager Derek Shelton will hand him the ball Sunday against the National League West-leading San Francisco Giants.

What you might conclude from those two statements is this season is as much about discovery and opportunity as it is trying to win games.

"We've got to find out more about our outfield group," general manager Ben Cherington said Friday before the second game of the Giants series at PNC Park. "Who can be part of what we're trying to build here?"

Of Keller, Cherington said, "It's important that Mitch continues to pitch."

Polanco, who's been in the majors since 2014 with 2,636 at-bats prior to Friday, is the highest-earning Pirates player with an $11 million salary this season, almost three times more than runner-up Adam Frazier ($4.3 million).

"We expect to continue to give opportunities to different guys just to learn more about them," Cherington said. "Gregory is one of those guys."

With a slash line of .202/.283/.337, Polanco is hitting .091 (2 for 22, nine strikeouts) with runners in scoring position, including 0 for 9 with two out.

When asked how long the Pirates can continue to allow Polanco to remain in the lineup, Cherington said, "There is no magic date or specific answer. We want to see improvement over time of that entire group.

"We continue to believe he can do that. He's healthy, and he's playing again now (after a short stint on the injured list). He still hits the ball hard. We still believe he can be a good major league player, and he's working hard towards that. We will continue to support him towards that."

Keller was the Pirates' top pitching prospect as recently as last year. He's since been replaced by 2019 No. 1 draft choice Quinn Priester, another pitcher.

Keller was the Pirates' second-round choice in 2014, the same year the previous management team chose shortstop Cole Tucker in the first round. Keller has four career victories. Tucker started this season in Triple-A Indianapolis.

Cherington said he has seen "flashes" of Keller's ability, and his work ethic hasn't faltered.

"We are encouraged and happy with his effort between starts, the things he's working on," he said. "Clearly, there's more improvement to happen. He knows that. We know that. There's been inconsistency there outing to outing in terms of bringing the practice work into the game."

Hayes progressing

Cherington said Ke'Bryan Hayes, who's been out most of the season with a strained wrist, will embark on a minor league rehab assignment before he's ready to play. No date has been set. He's eligible to come off the 60-day injured list June 3.

"He is progressing well. He had a good day (Thursday), says he feels great."

Cherington cautioned that there's more to Hayes' return than allowing the wrist to heal.

"We have to be mindful," Cherington said. "It's been long enough now since the first couple days of April (when he was injured) that we have to build the whole body up, not just the wrist."

Craig's keepsake

Shelton was pleased the spectator who retrieved Will Craig's first career home run Thursday night graciously gave it to the Pirates' first baseman. The Pirates thanked him with some team-issued equipment.

Shelton said he has two baseballs at home that commemorate memorable moments in his career — one from his first victory with the Pirates.

The other is the baseball used during a team in 2008 when the Cleveland Indians set the American League record for most hit-batsmen in a season (108). Shelton was the Indians' hitting coach.

Nice return, so far

Two of the four players acquired from the New York Yankees in the Jameson Taillon trade were spotlighted this week.

Miguel Yajure was the Pirates' starting pitcher Friday night, throwing five scoreless innings in the 3-2 victory against the Giants. Roansy Contreras of the Altoona Curve leads the minor leagues with 22 strikeouts in only 11 innings (two starts).

"He's always had a pretty good for feel for using his stuff inside the strike zone, even outside the strike zone," Cherington said of Contreras. "We like the athleticism and how he moves.

"He's been throwing all his pitches where he wants them for the most part."

Jerry DiPaola is a Tribune-Review staff writer. You can contact Jerry by email at jdipaola@triblive.com or via Twitter .