Mitch Keller has struggled early in Spring Training, but Sunday's start against the Rays may be a sign that the Pirates No. 1 prospect is turning a corner.

Keller, the No. 39 overall prospect, gave up one run on three hits, but also struck out five and lowered his spring ERA to 6.00. The strong outing was certainly welcomed after Keller had given up five runs in six innings over his first three spring appearances.

"I thought he executed really well. I was pleased with his slider," Pirates catcher Jacob Stallings said. "I think he’s a little bit more concerned about the slider than I am. I thought it was good.”

Keller, 23, certainly has the stuff to succeed -- a fastball that reaches the upper 90s, a power curve, slider and changeup -- but has struggled with command and consistency. A second-round pick from the 2014 Draft, Keller made his Major League debut last May, but struggled in the Majors and posted a 7.13 ERA over 11 starts (48 innings).

Here's how other top prospects performed on Sunday:

Alejandro Kirk, C, Blue Jays No. 5
Kirk only got to the plate once against the Phillies, but he took full advantage of the opportunity. The 21-year-old boosted his average to .429 (3-for-7) and hit his first homer of the year, a two-run blast, in Toronto's win over the Phillies. Kirk is looking to build off a solid 2019 campaign, when he hit .290/.403/.465 over 92 games across two levels.

Bobby Bradley, 1B, Indians No. 12
Bradley hit his third homer of Spring Training to highlight a 1-for-3 day at the plate. The 23-year-old has fared well so far this spring, batting .333 through 14 games. Power has never been an issue for Bradley, who hit a career-high 33 homers last year with Triple-A Columbus and has hit 23 or more homers in each of the past five seasons.

Justus Sheffield, LHP, Mariners No. 13
Sheffield retired seven of the first eight batters he faced as he carved his way through the Giants' lineup. The Giants did scratch across a run in the third inning, but overall it was a very solid outing for Sheffield. The 23-year-old, who has pitched to a 2.25 ERA this spring, gave up just the one run on three hits and struck out five.

Jazz Chisholm, SS, Marlins No. 3
Chisholm crushed his first homer of Spring Training, a no-doubter out to right, with a 112 mph exit velocity for his lone hit of the day. The shortstop finished 1-for-2, but also drew a walk and is hitting .308 through nine games. While Chisholm is expected to begin the season in either Double-A or Triple-A, it wouldn't be a huge surprise to see him quickly rise to the Majors at some point in 2020.

Albert Abreu, RHP, Yankees No. 11
Abreu cruised through two scoreless innings and retired five of the six batters he faced, while yielding one hit and striking out two. The 24-year-old, whom the Yankees acquired from the Astros in 2016, has plenty of potential and an impressive arsenal of pitches, but struggles with command and consistency at times. Abreu spent the 2019 campaign with Double-A Trenton, where he posted a 4.28 ERA over 96 2/3 innings.

Josh Fleming, LHP, Rays No. 28
Fleming gave up a run in the first inning, but promptly retired seven in a row to finish his outing. The 23-year-old struck out two, walked one and gave up just one hit as he tossed three innings of one-run ball. Fleming spent the bulk of last season with Double-A Montgomery, where he pitched to a 3.31 ERA over 21 appearances (17 starts) and earned a promotion to Triple-A Durham late in the year. With Durham, Fleming went 1-3 with a 5.14 ERA over 21 innings.

Zack Collins, C/1B, White Sox No. 10
Collins' strong spring continued with a 1-for-2 performance against the Royals. Collins, who is hitting .313 (5-for-16), gave the White Sox an early lead with a two-run homer in the second inning. Collins made his Major League debut in June last season and hit .186 with three homers over 27 games. With Triple-A Charlotte, where he spent the bulk of the 2019 campaign, Collins hit .282 and tied his career high with 19 homers.