ST. LOUIS -- Andrew McCutchen swung at a low fastball from Zack Thompson and caught it on the barrel of his bat. It came off hot, at 103.6 mph, and headed to a spot that tends to lead to automatic doubles for right-handed hitters: the right-field corner.

McCutchen put his head down and motored toward the first-base bag, rounded it aggressively then lifted his head and got bad news. Jordan Walker was retrieving it and preparing to fire it to second base. McCutchen would have been an easy out.

The veteran threw up his hands as if to ask, “What do I have to do to get a double there?”

Too often this season, it has been the Cardinals and their fans throwing up their hands when watching Walker play right field, but during the Cardinals’ 6-4 win over the Pirates on Sunday at Busch Stadium, everyone began to get a glimpse of the player Walker might one day be -- a powerful hitter with a cannon for an arm who can play good, if not Gold Glove-caliber defense.

“My reads aren’t where I want them quite yet, but they’ve been a lot better than at the beginning of the season,” Walker said.

Remember, this is a player who was moved to the outfield last season. He recalls a coach telling him to play outfield once during a summer ball game, but nobody hit the ball to him. The Cardinals drafted Walker as a third baseman, but they already have a great one of those in Nolan Arenado, so they began transitioning him into the outfield in 2022. This year, he has been among the worst fielding outfielders in baseball, but at age 21 with a deep skill set, that doesn’t figure to continue long.

The bat, as they say, plays. Walker also slugged a wicked line drive for a home run, his second in as many days, and is 10-for-his-last-18. Three of those hits have been home runs, and two of them have been doubles. What Walker has done this season, including accumulating a .794 OPS as a rookie, might be only a hint of what he might one day accomplish. His average exit velocities have ranked in the 70th percentile, and he is about seven years younger than the average Major League batter.

“When you’re a player with his skill set and aptitude, you’re bound to develop a lot quicker,” Cardinals manager Oliver Marmol said. “He loves the game. He loves working hard. And it’s a matter of time before we see a much, much better player, and we’re already getting a good version of him.”

Walker ranks in the bottom 1 percent for range (outs above average), and his fielding run value ranks in the bottom 3 percent, per Baseball Savant. His routes to fly balls sometimes are a bit circuitous. But his arm strength is in the 97th percentile and his sprint speed in the 80th, so there’s no reason he can’t become at least serviceable out there with experience.

He even stole a run with his legs Sunday, making a mad dash around third on a ball that Vinny Capra threw errantly to first. The throw came home, but Walker got his right hand around catcher Jason Delay’s tag with a clever slide to give the Cardinals a three-run cushion in the seventh inning.

Thompson is another former first-round pick the Cardinals would like to see get on a roll at the end of this season. If he does that, he’ll have an excellent shot of grabbing a rotation spot in 2024. Most of the other potential candidates have not made a better impression during this audition period.

Thompson pitched seven innings, holding Pittsburgh to three runs on seven hits while striking out six and walking none. For the season, he has a 3.91 ERA and 53 strikeouts in 46 innings with a 1.46 WHIP. Thompson had command issues at Triple-A, walking 39 batters in 34 1/3 innings, but he has mostly ironed them out. He has 18 walks in the big leagues this season.

Part of that could be the automated strike zone being used at Triple-A this season.

“To be completely honest, they cut a third of the strike zone off, and then I was trying to add in two pitches that I hadn’t thrown earlier in the season,” he said. “It was just kind of the perfect storm for me, and then getting back up here, I’ve been simplifying and just taking things one step at a time.”