BRADENTON, Fla. — The Mitch Keller Hype Machine just cranked up another notch.

Keller will start the season with Double-A Altoona, but his first brush with the big time arrived Sunday afternoon at LECOM Park, when he plowed through the seventh and eighth innings of the Pirates’ 2-1 loss to the Red Sox.

The Pirates’ top prospect — and one of the most promising pitchers in all of minor-league baseball — struck out three Sox and allowed just one hit. Just as importantly, he hummed his fastball in the mid-to-high 90s and flashed a cutting curveball.

To hear Keller tell it, he was happy to simply stay upright on the mound, surrounded by 9,000 of his closest friends.

“I was really nervous,” he said. “Very anxious. Just, it was a big moment for me, getting out there and showing people what I can do. It was a really cool experience running in from the bullpen and hearing the buzz around. It was cool.”

As if to reinforce the point that this was just a sip, not a swallow, of major-league activity, Keller had to hop a bus back to Pirate City across town immediately following the final pitch. Keller never spent a day in big-league camp this spring, despite getting a late-season promotion to Altoona in 2017.

While the only bonafide MLB players Keller faced were Rusney Castillo and Deven Marrero, he retired both on a combined four pitches. Clint Hurdle’s only previous view of Keller in competition came in instructional league, so he was anticipating Keller’s Grapefruit League debut.

“It’s nice to see one of our young men that’s having success that’s growing, that’s developing, to come out and perform in this arena as well,” Clint Hurdle said. “There was nothing to be disappointed about today. Efficient, crisp, downhill angle with the fastball, firm velocity.”

Catcher Jacob Stallings made one trip to the mound, in the eighth, to calm Keller’s heart rate and also review a couple of signs. Keller said they got crossed up once or twice, but thanked his battery mate for helping to make the experience productive.

When it came down to it, the strangest part for Keller was entering midgame, a first for the former Iowa prep star.

“I’d never come out of the bullpen before,” he said. “So it was kinda different, just sitting there and observing the game and getting all those feels coming in the game and what’s going on. Trying to take that and use it to get my adrenaline up and use it for the game.”

A 2018 arrival in the bigs will require Keller to do a lot of things right, but he’s shown few struggles with handling increasing expectations. In addition to owning the top spot in the Pirates’ system on our site and many others, Keller is a consensus top-20 prospect in all of organized baseball.

But every boost along the way helps. The Pirates clearly think there’s some value to giving their top guns a respite from Pirate City. Hurdle reminded that, early in his tenure, the team arranged for Starling Marte and Gregory Polanco to take a trip to Fort Myers to face the Red Sox, so they could have a pregame chat with David Ortiz.

“We believe in it a lot,” Hurdle said. “You know, we can watch a game like this and maybe not be really attached to it, but with these young men who come up, in some ways it may be the biggest game they’ve played in. It all depends on what their mind creates. I do believe there’s a lot of benefit to it.”

• With his father Kevin in attendance not long after his firing as the University of Pittsburgh’s men’s basketball coach, Stallings put forth the kind of performance that has him slotted firmly as the Pirates’ third catcher.

“We’ve liked him for a while,” Hurdle said. “If someone goes down … we have no hesitation of bringing Jacob into play.”

In addition to guiding Tyler Glasnow and Keller through fine performances, Stallings added a line-drive single and a lineout to shortstop, the latter of which ended the game with the tying runner on second base. He also threw out two would-be base-stealers with a release time Hurdle deemed as “major-league.”

“The bat’s come on,” Hurdle said. “I’m not sure anyone had the bat coming into play. I’m not sure he did at one point. But he’s put in work. He’s put in work and developed a routine and he’s stayed the course. He’s hitting the ball all over the ballpark, he’s making contact.

• Glasnow actually battled some bad luck in his otherwise promising start, as a broken-bat looper fell in for a hit and Mitch Moreland placed a bunt through the vacated left side of the infield for an opportunistic double.

Based upon Moreland’s spray chart, the shift was more than justified, not that Glasnow is about to complain about that sort of thing.

“I don’t think that’s my say,” he said with a broad smile.

• It’s looked for a while that Bryce Brentz has had the inside track to claim a spot on the 25-man roster as the fifth outfielder, but his performance in Grapefruit League hasn’t been terribly impressive. He went 0 for 2 Sunday (with a walk) to drop his exhibition batting line to .216/.326/.297.

The 6-foot, 215-pounder hasn’t looked out of place in corner outfield spots, but many of Brentz’s at-bats this spring have resulted in medium-depth flyouts. The 29-year-old slugged 31 homers for Triple-A Pawtucket last season, although he has just 90 major-league plate trips to his name.

“He’s a guy with a track record of power,” Hurdle said. “We haven’t gotten him synced up at the plate, to get some balls in the air. He’s getting closer. Spring training, again, is a tough gauge. We’ve fed him a lot of at-bats to see what he could do.”

• Across Tampa Bay in Dunedin, a split squad dropped a 5-2 decision to the Blue Jays, although Steven Brault (four innings, one hit, one strikeout, one walk) and Starling Marte (2 for 3 with a homer off J.A. Happ) provided highlights. Josh Bell and José Osuna each went 0 for 3.

With the final doubleheader day of the spring in the rear-view mirror, Monday looms as a probable cut day in the Bill McKechnie Clubhouse. There are 47 active players remaining in major-league camp, including 13 non-roster players.

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