JUPITER, Fla. — After seeing some of the same stuff from a different vantage point, Cardinals catcher Willson Contreras took a moment to review the pitchers he faced as a hitter during live batting practice Saturday so that he could detail what newcomer Riley O’Brien threw him.

“Kind of different? Used to start?” Contreras asked.

Seated beside him in the clubhouse, teammate Alec Burleson nodded.

“Just met the guy,” Contreras said.

“He struck you out,” Burleson reminded.

“Pretty nasty, I have to say,” Contreras smiled. “I was looking for a slider. He threw me that. Started in the middle of the plate and it ended up by the first baseman.”

Other than Sonny Gray’s enthusiastic narration of his bullpen sessions, the talk of Cardinals camp in its first week has been the “stuff” flying off the fingertips of young pitchers and newcomers such as Riley and that boomerang slider. As the Cardinals continue to audit and adjust the pitchers they acquire and develop, a focus has been outlier pitches — fastballs with giddy-up, spin rates that whirl, breaking balls that leave hitters in a seam-shifted wake, change-ups that vanish, deliveries that deceive.

In so many words, “stuff.”

“It was fun sitting in that bullpen and watching some of those arms go,” manager Oliver Marmol said. “There’s more depth than we’ve had in a while. Just stuff. You sit back there, and you watch some of these young guys put that ball in there. It’s real stuff coming out of their arms. That part is exciting. Now, it’s about getting out there (in games), see how they respond to certain things, and see how their stuff plays. A lot of the spring is like that.”

All around the six-pack of mounds the Cardinals use for bullpen sessions, the team has stationed tech. There is a high-speed camera stationed behind the fence at the catcher’s back. There are tripods holding up other gear that tracks body movements. There are radars for pitch metrics. And those are broadcast on screens were the pitcher and coaches can see instant info on the pitch speed, shape, spin, and break. They have everything there to get feedback on a pitch except arguably the one thing that matters most.

The hitters.

They stepped in Saturday.

Ramping up

The Cardinals organized their first live batting practices of spring Saturday, fanning out to four different fields and inviting hitters in camp to participate. With two games to start their Grapefruit League schedule next Saturday, most of the camp’s pitchers are throwing on the same day to prepare for those innings. Nineteen pitchers threw live BP on Saturday. (For context, Gray will be the only pitcher to face hitters Sunday; it will be must-see live BP.) Outside of games, the live BP can be valuable for the real teste of any organization’s development.

They have to take the right “stuff” and turn it into results.

“Some of it is funk, some of it is just the shape of the pitch being an outlier compared to the rest of the league of how much a pitcher moves horizontally or how much it stays above the zone,” Marmol said. “Just overall shape of pitches that lay outside the norm. Now it’s a matter of being ablet to get ahead in counts to get to that pitch. Or, throwing those pitches in more competitive areas where you can get chase. Some guys have big sweepers who are nasty and you look at their overall chase and it’s still below league average because they’re throwing it in an area where it’s a ball out of hand.

“(But) if you’re strictly relying on just command, it’s a tough place to be.”

On the “stuff” continuum, first-round draft pick Cooper Hjerpe and newcomer O’Brien occupy different ends to achieve similar results. From the right, O’Brien closes his back to the batter before unspooling his lean frame to produce a high-speed fastball and that slider. From the lefty, Hjerpe comes from a low arm angle and slings across his body that gives his pitches a trajectory hitters rarely see. That allows his 91 mph to 93 mph fastball to seem speedier. Or, as outfielder Lars Nootbaar said after facing him Saturday in live BP, “the angle makes it hotter.”

“You love that it’s not normal,” pitching coach Dusty Blake said. “A lot of hitters in this league calibrate to what’s normal and pitchers who throw pitches that tunnel with the rest of the league. He doesn’t do anything that aligns with that. It’s a tough transition for anyone who hasn’t seen him.”

Some teammates did that for the first time Saturday.

Drawing an audience

In his live BP, Hjerpe (starts with j, rhymes with chirpy) drew a group that included Nootbaar, rookie Masyn Winn and fellow first-rounder Jordan Walker.

“I wanted to take one, see one,” Winn said. “He threw it and it felt like he threw it out of the ground. I thought it was going to be low and it ended up right down the middle. He was dirty.”

Winn ended his at-bat with a groundout and offered Walker advice as they passed.

“Definitely upshoot,” the rookie said. “Definitely coming out of somewhere and climbing the ladder for sure.”

Hjerpe then struck out Walker and Nootbaar, swinging and looking, respectively.

Reading a live BP like a box score is a mistake, but what mattered from those three at-bats for Hjerpe were all the strikes. Last season, the lefty from Oregon State was limited to 49⅓ innings because of elbow pain that required surgery. Hjerpe felt sharp pain in his left elbow after an outing for Low-A Peoria, and at one point between starts his elbow locked up. During arthroscopic surgery, a doctor removed two pieces of loose cartilage, each 1-cm long. “Pretty significantly big,” Hjerpe said. A 20-min procedure beget a four-month rehab.

During his recovery, he was able to restore some of his delivery, including the angle of his lead foot that helps create a crossfire look. Hjerpe was able to return to games for a few innings at the end of the season — including eight in the Arizona Fall League. There, Hjerpe struck out 15 of the 37 batters he faced.

Those swings and misses that the Cardinals covet come with “stuff.” But what takes a pitcher from bullpen session darling to big-league pitcher is the step the Cardinals want to take with all young pitchers — and start this spring. To simplify to stats, consider walk rate and strikeout rate. In those 49⅓ innings, Hjerpe had 66 strikeouts and also 31 walks. A former starter in the minors, O’Brien struck out 504 in 439⅓ innings but paired that 10.3 strikeout-per-nine with a 4.5 walk-per-nine. In the briefest snippet of big-league experience, O’Brien has more walks (four) than strikeouts (three).

“There is a gap between their walk rate and their strikeout rate and you’re trying to figure out ways to get them more in the zone,” Marmol said. “We’re working on those guys that do have stuff that fit into the bucket you just described — commanding the baseball a little more while not losing some of their swing and miss. … I don’t think you have to pick one or the other. You’re hoping to have stuff that you can command. But you can’t just create stuff.”

And stuff matters.

Marmol said, describing specifically how they’ll stock the bullpen: “I mean, we’re going to take the guy with the best stuff, gives us the best chance.”

O’Brien is in that competition.

He cautioned about reading too much into the results of his first live BP, stressing that pitchers are “a bit ahead of the curve” on the hitters, that his stuff gives him an advantage when a hitter first sees him, especially if he’s one of the first pitchers they’ve seen in months.

“Obviously, though, getting swings and misses is good feedback,” he said.

Before leaving the clubhouse Saturday, Contreras walked over to O’Brien at the pitcher’s locker and gave him a fist bump.

“It’s good to have that kind of stuff on our staff,” the catcher said.