WILLIAMSPORT, Pa. -- Before the Pirates’ 7-1 loss to the Cubs on Sunday night -- their 27th defeat in 34 games since the All-Star break -- general manager Neal Huntington settled into the small broadcast booth at Historic Bowman Field for his weekly radio show with broadcaster Greg Brown. Near the end of the show, Huntington fielded a question about the club’s 2020 rotation.

Perhaps fittingly, most of Huntington’s answer consisted of more questions.

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“How do we get Joe Musgrove to continue to turn that corner, the things that we’re seeing? How do we continue to get Chris Archer to be Chris Archer again? How do we get Mitch Keller to take that next step forward?” Huntington said on KDKA-FM. “How do we help Trevor Williams go back to being as good as Trevor Williams was the second half of last season? … Can we continue to get Steven Brault to continue to push this forward? … What, externally, is available for us?”

The Pirates will spend the next six weeks evaluating the pitchers who might start for them in a 2020 rotation that will be without ‘19 Opening Day starter Jameson Taillon all season. One of them is Keller, their top prospect, who gave up six runs on seven hits over 4 1/3 innings in the Pirates’ loss to the Cubs on Sunday night in the third annual Little League Classic presented by GEICO.

Keller will likely remain in Pittsburgh’s rotation the rest of the season, starting every fifth day with a chance to prove himself worthy of a spot entering next year. He took a step in that direction last time out, allowing only two runs (one earned) over five innings while picking up his first Major League win in Anaheim, only to take a step back against the Cubs.

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The 23-year-old right-hander only allowed one home run in his first four starts combined, but the Cubs’ first two hits against him landed over the Minor League ballpark’s outfield fence. Nicholas Castellanos took Keller deep in the first inning, and Jason Heyward lined a 1-0 pitch over the left-field wall in the third inning.

“Whenever you make mistakes, those guys are very, very good hitters who are going to make you pay,” Keller said.

Meanwhile, the Pirates managed only five hits and struck out seven times against veteran Cubs lefty Jose Quintana. They finally got on the board in the ninth, when Starling Marte blasted Craig Kimbrel’s first pitch out to left-center field for his 21st home run of the season. They finished the night 0-for-9 with runners in scoring position, dragging their two day total down to 0-for-21.

Keller ran into more trouble in the fourth, giving up two runs on a single by Kyle Schwarber, and Keller exited the game with one out in the fifth after serving up a pair of doubles to Heyward and Kris Bryant. Anthony Rizzo greeted reliever Chris Stratton by blasting a two-run homer off the scoreboard in left-center field.

"I thought he showed some of the things we were looking to see and we want to continue to see,” Pirates manager Clint Hurdle said. “And I think he's shown some opportunities for growth, some finishing of pitches we've got to work on."

Five starts into his big league career, Keller has an 8.86 ERA and a 2.02 WHIP. He’s done some things well, like striking out 24 batters in 21 1/3 innings and mixing pitches like he did last Monday in Anaheim. But the Pirates’ rotation, now and in the future, is in greater need of production than potential.

"I'm not happy, by any means. Yeah, frustrated,” said the typically even-keeled Keller. “It's just back to work tomorrow. Got to have that mindset.”

For Pittsburgh to stand any chance in 2020, especially with Taillon recovering from his second Tommy John surgery, multiple starters will need to step forward into more prominent roles.

There have been hints of progress and signs pointing in that direction lately. Musgrove worked 7 1/3 excellent innings Friday and ended with a no-decision. Brault put together the best start of his career on Saturday, and he has a 2.58 ERA over his last 10 starts; granted, the Pirates have lost seven of those 10 games.

But Musgrove, Archer and Williams lead the team in starts, and none of the three has an adjusted ERA equal to or better than the league average this season. Huntington preemptively tempered expectations about the club's offseason activity by suggesting the Pirates need to find the next Francisco Liriano or J.A. Happ, veterans who were considered reclamation projects before Pittsburgh turned them into well-paid free agents.

It’s unfair to place too much pressure on one pitcher, much less a rookie who’s made five up-and-down starts in the Majors. But Keller might represent the Pirates’ best-case scenario for internal improvement, someone who can answer one of Huntington’s questions. He’s ready to start proving it.

"I'm thankful for every shot I get up here,” Keller said. “I need to be better and use these experiences to hopefully help me along the way in my career. Hopefully we'll get some more wins.”