Hutchison and Glasnow have an advantage for different reasons. Hutchison has by far the most Major League experience. Glasnow has by far the highest ceiling -- he is the Bucs' top prospect and MLBPipeline.com's No. 9 overall prospect for good reason.
But Brault would be the only left-hander in a right-handed rotation, and Williams is the kind of ground-ball pitcher the Pirates covet. So it figures to be an open competition this spring.
Hutchison will earn $2.3 million this season after coming to Pittsburgh as the Pirates' lone return in the deal that sent Francisco Liriano and prospects Reese McGuire and Harold Ramirez to Toronto. The 26-year-old right-hander owns a 30-21 record and 4.93 ERA in 82 big league appearances, including 74 starts.
Hutchison's best season came in 2014, when he posted a 4.48 ERA (noticeably higher than his 3.85 FIP) in 184 2/3 innings over 32 starts. His peripheral numbers were encouraging, as he struck out a batter per inning and walked fewer than three per nine.
The Pirates have said since August they targeted Hutchison as a contractually controllable starting pitcher with attributes they like. Perhaps he will emerge this spring as the latest arm to benefit from working under pitching coach Ray Searage.
Glasnow struggled in his brief debut, but the Pirates believe he can be a top-of-the-rotation starter with refined mechanics and a better changeup. The 6-foot-8 righty has consistently dominated Triple-A competition and could earn a spot if he takes noticeable strides this spring.
"Trust me, if Tyler Glasnow is ready to help us at the Major League level, that's a good thing for us, and we'll absolutely give him that opportunity," Huntington said. "If he's not, we'll continue to work to help him get ready. When he puts this all together, he's going to be a fun pitcher to watch."
Williams showed a glimpse of his potential in his first Major League start, breezing through four innings facing the minimum 12 batters, but he mostly pitched out of the bullpen last September. He boasts excellent Triple-A numbers, including a 2.53 ERA in 23 outings, and he frequently induces ground balls.
Brault had an up-and-down debut, but Huntington attributed some of his struggles to an early-season hamstring strain. Before the injury, Huntington said, Brault looked like a different pitcher.
"More power, more quality of stuff, more crispness of the stuff," Huntington said. "If that guy's back again, he's going to open some eyes."
Brault's standing as the only lefty in the competition won't hurt his chances, but that won't be the deciding factor.
"In a perfect world, you want balance in your rotation," Huntington said. "We also want to take the five guys that we feel put us in a position to win most consistently."
Adam Berry has covered the Pirates for MLB.com since 2015. Follow him on Twitter and Facebook, read his blog and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.