The baseball men running the Washington Nationals know conclusions should not form in one spring training week, but with Anthony Rendon they can’t help themselves. Front-office officials watch his sweet swing and whisper he’ll hit third someday. Scouts watch him field groundballs and declare he could win a Gold Glove. Coaches throw him batting practice and shake their heads.

The Nationals drafted Rendon out of Rice with the sixth overall pick last year, and they assigned him to major league camp because his draft deal stipulated he be placed on the 40-man roster. He will not make the major leagues out of spring training. But based on the early reviews, Rendon, 21, is not long for the minors.

His future contains one uncertainty. Rendon played third base in college, but after Ryan Zimmerman signed his six-year, $100 million contract extension Sunday that includes full no-trade protection, the Nationals already have their third baseman.

“They had to lock him down,” Rendon said, smiling. “He’s done great for this organization. He’s a great player. Why wouldn’t you want to lock him down?”

Zimmerman’s deal, for now, will not alter the Nationals’ plan for Rendon. He will alternate between third base, shortstop and second base during spring training. When he begins his minor league season — likely at Class A Potomac, perhaps Class AA Harrisburg — he will play third base, period.

Rendon feels comfortable at both second base, where he played last year at Rice upon returning from a shoulder injury, and shortstop, where he played through high school. The Nationals are confident his slick fielding will translate anywhere in the infield.

“Watch his hands,” said Bill Singer, the team’s director of pro scouting, while watching Rendon field grounders at shortstop. “He makes it look like he never gets a bad hop, because his hands are so soft and quick.”

Some have wondered if Rendon’s defensive ability could one day force Zimmerman to move positions. Zimmerman struggled as he overhauled his throwing mechanics last year, but by the end of the season had minimized doubts about his arm.

“I think I want to play third base until someone is better than me at it,” Zimmerman said before camp began. “If that means me playing third base for five more years and then moving somewhere because someone is better than me at third and it’ll help us win, then I’ll do it. If that means me playing third base for 10 years and then going to first base or wherever, then I’ll do it. I don’t care.”

The Nationals will find a place for Rendon because of his bat. Nationals scouting director Kris Kline called him “the best hitter in the draft” last year. When asked about Rendon’s swing, third base coach Bo Porter smiled, shook his head and said, “Ooooh!”

Last week, Porter threw batting practice to Rendon, and after Rendon sprayed line drives, Porter approached him. “I had your swing before the accident,” Porter said.

“What accident?” Rendon asked.

“I was born,” Porter said.

After assistant general manager Bob Boone watched Rendon hit one day, he turned to Johnson and said, “Anthony swings like you did.” Johnson, standing behind the batting cage, could have taken Boone’s comment one of two ways.

“I thought it was much more of a compliment to me than it was to him,” Johnson said. “He’s special.”

Rendon, listed at 6 feet and 190 pounds, generates power with a quick, easy wrist movement. It looks like he is swinging at half-speed, until the ball rockets off his bat.

“I’ve been watching him more, because the first day I realized the ball really does jump off his bat,” said Mark Teahen, a veteran in the same batting practice group as Rendon. “When you see him, you don’t look at him and think, ‘That guy has a lot of power.’ He doesn’t jump out at you. But it’s easy pop for sure. He puts the barrel on the ball, and it just goes.”

When Porter watches Rendon hit, he sees a fully developed swing — he covers the entire plate, smacks line drives to all fields and generates backspin, which allows the ball to carry.

“His power numbers are going to improve as he gets older,” Porter said. “As he gets stronger as he starts to develop even more, he has the ability to grow into a guy who’s going to hit for power.

“It’s a fluid, loose swing. It’s a clean delivery of the barrel. When you get guys like that out of the draft and they’re that polished, you shake your head and go, ‘Now that’s a good swing.’ ”

Growing up in Houston, Rendon worked with hitting coach Willie Ansley, a former Astros farmhand. Ansley repeated to Rendon, “Put the barrel on the ball, and good things will happen.”

Otherwise, Rendon has no explanation for the way he developed the swing that has the Nationals’ staff raving. “Your guess is better than mine,” Rendon said. “I didn’t do anything special growing up. I guess I just had it.”