BOSTON -- He's all all of 19 years old, but at some point early in the 37 games that currently comprise his life as a big leaguer, somebody made the observation that if you watch Bryce Harper play nine innings of baseball, you’re bound to see him do something special.

Then there are nights like Friday. When he seems to do everything special.

He showed the speed necessary to turn Jarrod Saltalamacchia’s sure-double into a snow-cone catch. He ripped a homer to dead center among his three hits. And finally, for good measure even if it was ultimately inconsequential, he one-hopped a throw to home plate — flat-footed — from the base of the Green Monster.

It was an impressive introduction to Fenway Park, even if it was hardly an introduction to the fans who exactly three years earlier had seen him cast as “The Chosen One” on the cover of Sports Illustrated, who’d been hearing tales of his legend and lore ever since — and who couldn’t have been disappointed by their first glimpse of the can’t-miss kid who has already become a can’t-miss attraction.

“Harper was amazing,” said Red Sox manager Bobby Valentine. “Everything he did out there, including catching that ball that Salty hit in the gap — he came out of nowhere to catch that. He threw the ball from the wall one hop to home in the ninth. Hit some pretty good breaking balls off of lefthanders, one for a hit to left, one for a groundout to short that he almost beat out.

“He’s very impressive.”

Harper’s homer was his sixth, his double was his eighth, and he entered Saturday’s evening affair hitting .288 with an .899 on-base plus slugging after becoming the youngest player with three hits at Fenway since Ken Griffey Jr. did it in 1989. It also brought him to .354, with 12 runs batted in and 14 runs scored, in his previous 16 games.

Those numbers are nice, and certainly good enough to justify the Nationals’ decision to ditch their plans of sending him back to the minors after he plugged a need created by injury. But at this point with Harper, it’s more than merely his production.

It’s his presence, it’s the perpetual chance that greatness is just a pitch away, it’s the pure star power that together explain why on a night when fellow phenom Stephen Strasburg strikes out 13 Red Sox over six innings, Harper’s blend of energy and ability still leaves just as strong an impression.

“He’s got a good swing,” Saltalamacchia said. “The one he hit out was a fastball that just stayed out over the middle of the plate, and he put a good barrel on it. Threw one away on him second at-bat and he hit in the gap. He’s definitely a good player. Plays hard. He’s not an easy out; he’s a tough out.”

“Plays the game hard,” said Sox first baseman Adrian Gonzalez. “Great power, great bat speed. The single he got off of Rich (Hill) was pretty impressive — he was able to stay on it. There’s a lot of talent there.”

The questions put to Valentine, Saltalamacchia and Gonzalez didn’t lead any of them to any particular moment in Friday’s game — yet consider their responses: Between the three of them, choosing only from a single game, they collectively cited six different plays on which Harper impressed them.

The kid is special, indeed.

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Even after working Brian Matusz of the Orioles for five free passes Thursday night, the Sox entered the weekend having walked in just 7.7 percent of their plate appearances this season — a frequency putting them on pace to equal the 1963 and 1980 clubs for the franchise’s lowest walk rate since 1931. (Incidentally, that team of 81 years ago finished 62-90, and last among AL teams in both hits and runs.)

The trend began last season, when Boston’s 9.2 percent walk rate was the organization’s lowest since 2002. And the explanation appears to lie in diminished selectivity at the dish. From 2003-10, the Sox swung less often than any team in the majors, hacking at 43.3 percent of all offerings over that span. In 2011, that spiked to 45.2. Before Thursday it was 45.6 in 2012, which was more often than 18 other teams.

This was despite the fact the Sox were seeing fewer pitches inside the zone (45.9 percent) than they did in any season from 2002-10 (during which they saw 51.3 percent strikes). Additionally, this year’s Sox were swinging at 29.1 percent of pitches thrown outside the zone — a steep climb from the 20.8 percent they strayed to swing at over that same nine-season span.

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After the leadoff walk he issued to Mark Reynolds turned into the game-winning run on Tuesday night, Alfredo Aceves understood his mistake.

“Every walk that you walk is going to score,” he said, “100 percent.”

That’s not quite true — but in terms of leadoff walks, it’s been no exaggeration for Aceves. Entering Saturday, the Sox closer had walked the leadoff man four times in the 30 innings he’d started this season. All four had led to a run scoring in that inning. Conversely, when managing to avoid walking the first hitter, Aceves had been scored upon in just three of 26 frames.

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Even as he establishes himself as one of the AL’s premier offensive catchers, opposing baserunners may be exposing Saltalamacchia as a defensive vulnerability. After the Nationals swiped two bags on Friday, he’d thwarted just five of 34 attempted thefts, and just three of 29 at second base.

Compounded by six errors, his 14.7 percent success rate in nabbing thieves was significantly lower than the major-league average of 27 percent.

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STAT OF THE WEEK: Since ending his season-opening string of six starts in which he allowed at least five earned runs, ’s ERA is 3.10, with 1.23 walks and hits per inning pitched, and a 1.86 strikeout-to-walk ratio. Over his three previous seasons, Buchholz’s ERA was 3.10, his WHIP was 1.27, and his K:BB ratio was 1.85.

Dave D’Onofrio covers the Red Sox for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com.