Bishop Gorman came into the tournament ranked No. 2 in the country by Baseball America, and Gallo -- ranked No. 19 on MLB.com's Top 50 Draft Prospects list -- expected to showcase his power from the left side at the plate, and his strong right arm, both from third base and the mound.
So far, it hasn't gone as planned.
Bishop Gorman has gone 1-2, losing, 10-3, to 18th-ranked Mater Dei (Calif.) and, 7-4, to unranked Gulliver Prep (Fla.) and beating top-ranked Carroll (Texas), 8-4. Gallo has just one hit in eight at-bats, with four strikeouts. He singled in two runs in the victory over Carroll.
On the mound, Gallo gave up five runs, though all unearned, and took the loss against Gulliver Prep. He did strike out seven in three innings.
Gallo is philosophical about the showing so far.
"It kind of gives us that reality check that we're not gonna beat everybody, 10-0, like we do at home, that these teams are good, and they'll beat us," he said. "They're just as good as us."
Time for another reality check: Nothing Gallo does in this tournament at the USA Baseball National Training Facility will change Major League scouts' opinion of him.
A 6-foot-5, 225-pound power hitter with an arm capable of hitting 97 or 98 mph on the radar gun, as he did Thursday, Gallo has skills they covet.
And the NHSI is just another moment in time.
As hard as it is to watch, Gallo's father, Tony Gallo, understands that.
"I think he's pressing a bit," Tony Gallo said, pointing out that that's not unusual for kids trying to impress scouts and recruiters. "It's their senior year, and they're pressing. They want to do the absolute best they can, and sometimes that will mess you up a little bit."
Joey Gallo agreed but said it's also about finding a rhythm, like the rhythm he had when he hit six home runs in a single tournament earlier this year.
"When we were in that tournament, I just started hitting, and then you can't go wrong," he said. "Then you get in a little slump and you can't get out of it. You put a little more pressure on yourself.
"I try to take it game by game. I'll go out tomorrow and play hard and try to compete and try to forget about it."
Mater Dei came in with a plan of attack for Gallo, echoed by coach Burt Call and Game 1 pitcher Davis Tominaga: Hard in, then soft away. Tominaga threw a pitch in each of Gallo's four plate appearances that backed Gallo off the plate -- "basically at my head," Gallo said -- then went away with changeups and curves.
The one time Tominaga got too much of the plate on a fastball, Gallo hit it nearly 400 feet, foul.
"Hard fastballs high and inside, and changeups down and away," Gallo said. "And they got me."
Against Gulliver Prep, Gallo struck out three times, and afterward didn't remember seeing a fastball.
Bishop Gorman coach Nick Day said the answer might be for Gallo to get back to hitting the ball to the opposite field.
"He has great power the other way. He hits the ball well the other way, and that's why we're pushing him to get back on track and hit the ball the other way," Day said. "When he does do that, he's the Joey Gallo who gets all the love and prestige and all that stuff."
Tony Gallo says that will happen soon.
"It'll come," he said. "What they say is it comes in blocks. It's not the one game with three strikeouts and they say, 'He can't hit.'
"Tomorrow could be better, and the day after, and he goes home and gets in league play and he starts to do well, and it's pretty much all forgotten."
One day soon, high school baseball will be over, and there will be decisions to be made. Gallo is committed to a baseball scholarship at LSU, but being ranked No. 19 on MLB.com's list of top prospects for June's First-Year Player Draft probably means he's bound for professional baseball.
Which of his skills do teams covet the most?
Tony Gallo, who for 10 years has been a pitching coach in Las Vegas, knows what the organizations think. All but one team has had an in-home visit with Gallo -- the last team is in the process of scheduling one -- and the message has been consistent.
"When teams come to our home, they're all talking about him as a power-hitting third baseman," Tony Gallo said. "If a move were to come, it would be because he has outgrown third, and it would more than likely be right field because of his arm."
What about first base? That's where Gallo played for Team USA in the 18U Pan American Championships, winning a gold medal.
"It would be a waste of his arm to put him at first base," Tony Gallo said. "He's an accomplished first baseman, but everybody is looking at him as a third baseman.
"That's really where every team has seen him. No team has come in and said, you know, pitcher, or first base. They always start [with third base], and say, 'Until you play yourself out of it, that's where we're going to put you.'"
Others see Gallo's arm and, knowing he's the son of a pitching coach and has a high-90s fastball, wonder why he's not a pitcher.
Joey Gallo describes his strengths as a pitcher as his fastball and a good changeup, when it's going.
Thursday was his first outing on the mound this season, necessary because of the NHSI's four-games-in-four-days format. As a junior, he pitched 18 2/3 innings all season for Bishop Gorman.
"I haven't been pitching too much," Gallo said. "I just go out there and try to compete, really."
His father says pitching has never been the plan.
"Obviously they don't want to take the bat out of his hands," Tony Gallo said. "The reason we did the pitching part with Joey is because we knew he had a strong arm and we wanted him to learn it correctly.
"We haven't really worked all that much, just basic mechanics to keep him healthy."
The focus is on hitting. And on breaking out of this slump, making more consistent contact and hitting for a higher average. He's working with four-time National League batting champion Bill Madlock, among others.
"He's getting there," Tony Gallo said. "I see the adjustments coming. He's closed up a little bit and shortened his swing, as short as a 6-5 guy can have."
Through it all, Joey Gallo has kept working. He hits every day, and his confidence level is still high despite his struggles in the NHSI.
"Does he have a hole?" Gallo said. "Everybody has a hole. A major leaguer has a hole. We're not really worried about that.
"He's a kid, but he doesn't give up. You can tell by the way he plays the game."
When the rough patch ends, and Day is confident it will, watch out.
"I know at some point he's going to relax and get back on track, and when he does, he's going to be the old Joey," Day said. "And he's going to be phenomenal."
Mike Persinger is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.