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Nearing the end of his remarkable rookie season, any swing Bryce Harper takes may generate history. As the year draws to a close, he has already arguably had the greatest season by a teenage hitter of all time. Pick a category, and he’s probably threatening to top it.

Most jarring, Harper could surpass Mel Ott’s 1928 season for the most wins above replacement since 1900 in a single teenage season. We are talking the FanGraphs version here, and that is always tricky because its defensive component can be unreliable in a one-season sample. Now that the caveat is out of the way, here it what makes your eyes go wide.

In 1928, Mel Ott punched up a 4.6 WAR as a 19-year-old. The second-highest for a position player before Harper came along was Ty Cobb, who had a 3.1 WAR in 1906. At the moment, Harper has produced 4.5 wins above replacement, going by FanGraphs. By that respected measure, with six decent games, he will produce the most valuable season by a hitter younger than 20.

Notice the use of “position player” and “hitter.” Dwight Gooden blows away all comers with his 8.6 WAR season at age 19 in 1984. Because baseball is just so great to us, Gooden’s manager that year was none other than Davey Johnson.

Harper’s WAR total speaks to his standout defense, which FanGraphs ranks among the best in the league. He still has his mishaps, like the line drive that sailed over his head Wednesday for a Kevin Frandsen triple. But he also has a cannon for an arm and can cover a lot of ground.

Solely at the plate, Harper still has a chance to wind up on top of a few all-time, single-season teenage leaderboards. This is a rundown of where he stands in what categories, and whom he is chasing with six games left.

Home runs: 21, second (Tony Conigliaro 1964, 24)

Runs: 94, second (Buddy Lewis 1936, 100)

Steals: 17, second (Ty Cobb 1906, 23)

Doubles: 23, tied for fourth (Phil Cavaretta 1935, and Robin Yount 1975, 28)

Triples: 9, fifth (Buddy Lewis 1936, 13)

Walks: 54, second (Rusty Staub, 59)

OPS: .799, third (Mel Ott 1928, .921)

(Harper has most often been asked about his home run total, but Wednesday night he gave an interesting response to a question about potentially catching Conigliaro’s 24: “I like those runs a lot better. Just getting on base, letting them get those ribbies and whatnot, getting things going. Getting on base for all the guys to drive me in, being key in that aspect, doing things on the base paths, I think that’s huge.”)

What’s odd is, despite the historic nature of his season and the unstoppable hype surrounding him, Harper does not look like a sure thing for Rookie of the Year. In fact, Arizona Diamondbacks’ right-hander Wade Miley seems to be the leading candidate. He was the choice in this week’s Sports Illustrated, and a few writers have talked to like Miley.

Miley has a strong case. He is 16-11 with a 3.32 ERA with 134 strikeouts over 187 innings. FanGraphs puts his season at 4.5 WAR – dead even with Harper. It is difficult to measure a pitcher vs. a hitter in an award debate, and that sure doesn’t make it any easier.

By the way, this will deserve its own blog post at some point, but I’ll go record to say that whatever happens in the rookie of the year voting, Bryce Harper is going to win the National League MVP in 2013. The quick version goes something like this: The league overwhelmed Mike Trout at 19, and at 20 he is about to win the AL MVP over a slugger poised to claim the Triple Crown. Harper had his struggles, but for two long stretches he murdered the ball, played a premium defensive position at a high level and ran the bases like a freight train. What he has done at 19 has perhaps been unprecedented; what he could do at 20 is unthinkable.