“When I walked down the street, people would’ve looked, and they would’ve said, ‘There goes Roy Hobbs, the best there ever was in this game.”

— Robert Redford, “The Natural”

“Be considered the greatest baseball player who ever lived.”

— Bryce Harper, the National

The Washington Post’s Mike Wise offers his extra points about Bryce Harper and his future professional baseball career. (Post Sports Live)

Sometimes, reality comes straight out of central casting.

Bryce Harper, whose first season in the major leagues as a 19-year-old earned him National League rookie of the year honors, could be on the verge of even bigger things in his 20-year-old campaign.

Here is an unofficial list of some of the greatest seasons by 20-year-olds:

●Ty Cobb, 1907: 212 hits, 53 stolen bases, .350 average

●Mel Ott, 1929: 42 home runs, 151 RBI, .328 average (and only 36 strikeouts)

●Ted Williams, 1939: 31 home runs, 145 RBI, .327 average, 344 total bases

●Al Kaline, 1955: .27 home runs, 102 RBI, .340 average, 321 total bases

●Alex Rodriguez, 1996: 36 home runs, 123 RBI, .358 average, 379 total bases

Ken Griffey, Jr., Mickey Mantle, Frank Robinson, Johnny Bench, Jimmie Foxx were also tremendous at 20. And for the Moneyball set, no one thus far mentioned can top Mike Trout’s 2012 wins above repacement figure of 10.9 — a stat that takes defense into account.

But Harper could be better than all of them at that age — even the kid who became the youngest batting champion in American League history 58 years ago.

“I was good at 20, but maybe not as good as he is,” said Kaline, 78, by telephone from Comerica Park in Detroit on Saturday afternoon. “I love Bryce Harper. I think he’s only scratched the surface. When I look at him, I see this very confident young man, a player who just busts his butt and leaves it all on the field.”

As the ball leaped off the fat part of a bat Saturday afternoon in Cincinnati, leaving Great American Ball Park on a lead-core line for his third home run just five games into the new season, Harper was already being hailed as an MVP candidate and, along with Trout, one of the premier position players in baseball for possibly the next 15 years.

But lately, a newfound fascination for his talent and ‘tude has consumed baseball and beyond.

Maybe because last week he became the youngest player in the game’s 142-year-old annals to hit two home runs for his team on his first opening day. Or perhaps because a scout last month told ESPN’s Buster Olney that Harper’s swing reminded him of “controlled violence.” Maybe because he’s so good and so young it doesn’t feel like he skipped a grade as much as a generation.

Whatever, the awe and wonder that accompanied Harper at 19 hasn’t abated at all at 20, which makes him the youngest player in the National League. A staggering fact: Harper would be the third-youngest player at Class AA on opening day.

“His ability is obviously off the charts, but the reason a lot of baseball people say, ‘This guy plays the game right,’ is the way he hustles all the time,” said Nomar Garciaparra, a six-timeall-star who is now an ESPN analyst. “As a former ballplayer, the way he runs the bases and goes after balls is what grabs you the most.”

Garciaparra carefully watched Harper against the Marlins on first base on Thursday afternoon. He watched Harper’s movements, his timing, his demeanor — everything.

“As soon as the ball was hit, he took off for home — and he almost caught Jayson Werth as he slid hard into the plate. The amazing thing is, he was thinking home right off the bat,” Garciaparra said. “He was thinking, ‘I can score on this. And the only way I don’t is if the third-base coach stops me.’ That was his thought. That’s why people in baseball who played at this level are blown away by him.”

Peter Gammons, one of the game’s most respected chroniclers, believes Harper has a chance to be better than “most of the best 20-year-olds to ever play the game” for two reasons:

“His drive and respect,” Gammons said. “He plays with the passion of a George Brett or Pete Rose but he also has an uncommon appreciation and respect for the game. I look at Trout and him and who they are as people in this day and age of the spoiled young athlete and I think we should all be thankful we don’t have two indulged jerks.”

Gammons still recalls being told by Harper when he was in the Arizona Instructional League at age 17 that Brett was a player he wanted to pattern his game after. “When I told George, he replied, ‘He has to be the only 17-year-old in this country who knows who I am.’ That’s who Bryce Harper is. He gets it when so many others don’t at that age.”

When a writer once told Harper he used to cover the Tigers, Harper floored him by knowing that Kaline had become the youngest AL batting champion in 1955. When that story was relayed to Kaline on Saturday afternoon, he paused over the telephone.

“Really?” he said. “Usually young players don’t know players who came 20-25 years before them, let alone 50. I’ve always wanted to meet Bryce Harper. I hope I get a chance soon.”

Let’s take that last sentence in for a second: Al Kaline hopes to meet Bryce Harper.

“The reason I think he can be as good or better as all of us at that age is also because of his size,” added Kaline, who was listed at 6-foot-1, 175 pounds but confessed that he was probably 155 pounds when he came to the Tigers as a teenager. “He’s just so much bigger and stronger.”

At 6-2, 230 and with a muscled neck with roughly the circumference of a propane canister, Harper is two inches taller and 45 pounds bigger than Brett. He’s got three inches and 35 pounds on Rose.

The next Charlie Hustle is basically Chuck Hyper, Bam-Bam in a batting helmet. Harper is barely out of his teens, but he’s already among the best young players ever and, perhaps one day, the game — which, of course, is dangerous to even think about.

“You don’t forget the age, but what we need to forget about is trying to compare,” Garciaparra warned. “We get caught up so much in trying to compare somebody to other greats and put more expectations on them. ‘Well, gosh, Ken Griffey Jr., did this.’ Wait a minute — we’re already comparing him to a Hall of Famer? Give him time to just be Bryce Harper. That’s enough right now.”

For more by Mike Wise, visit washingtonpost.com/wise.