This might be MLB's most feared hitter

Exactly what kind of hitter is Bryce Harper? A look at his career stats reveals that to be a complicated question, as the talented 26-year-old looks to land a record free-agent contract this offseason.
Over the past five years, Harper has hit like an inner-circle Hall of Famer (2015), a solid starter ('14, '16) and an All-Star ('17-'18), tantalizing with his hot streaks and frustrating with his (sometimes injury-fueled) cold stretches.
• The latest Harper free-agent rumors
One thing has remained consistently true, however. Pitchers fear Harper -- more than just about any other big league hitter.
Their extreme caution in how they approach him is both a blessing and a curse, with Harper racking up walks (an MLB-high 130 in 2018), but losing opportunities to do damage. So as he moves forward -- whether that's back in Washington or with a new team -- much will depend on Harper's ability to squeeze the most out of the chances he gets.
One way to quantify how pitchers view Harper is to look at their location against him.
To that end, we can use Statcast™'s detailed strike zone, which is broken down into three regions. "In-zone" pitches are clear strikes, "out-of-zone" pitches are clear balls and "edge" pitches fall in between, just on either side of the zone's border.
Here is where Harper ranks, over the past three years, in terms of his percentage of "out-of-zone" pitches seen -- in other words, pitches a hitter should almost never want to attack.
2016: 41.8 percent (Highest of 302 hitters)
2017: 37.7 percent (seventh highest of 314 hitters)
2018: 39.0 percent (third highest of 308 hitters)
Minimum 1,000 total pitches seen
Lumping those past three seasons together, pitchers have thrown nearly 40 percent of their offerings to Harper to this region well outside the zone. They have done this despite Harper swinging at those pitches significantly less often than the MLB average, and less often than most other hitters who have been approached in similar fashion.
Highest percent of pitches seen outside edges of zone, 2016-18
Min. 3,000 total pitches seen (301 batters)

1. Giancarlo Stanton: 39.9 percent (20.3 percent swing rate)
   2. Bryce Harper: 39.6 (16.5)
   
2. Javier Báez: 38.7 (33.7)
   
3. Aaron Judge: 38.3 (15.0)
   
4. Kendrys Morales: 38.0 (22.5)
   
5. Joey Gallo: 37.6 (18.4)
   T-7. Adrián González: 37.3 (20.9)
   T-7. Gregory Polanco: 37.3 (18.4)
   T-9. Carlos González: 37.1 (22.9)
   T-9. Salvador Perez: 37.1 (35.0)
   MLB averages: 32.9 (19.0)
   The visual below illustrates the challenge Harper faces by putting his 2016-18 pitch map side-by-side with those of two other established left-handed hitters, Nick Markakis and Dee Gordon. Markakis sees pitches outside the edges of the zone at a rate near the MLB average, while Gordon does so at a much lower rate.
   
   Opponents have good reason for sticking with this approach against Harper, who punishes mistakes but doesn't stand out as a bad-ball hitter. Over the past three seasons, he slugged a robust .805 against those clear strikes inside the edges of the zone, one of the best marks in MLB. On all other pitches, he slugged a middle-of-the-pack .310.
   It's the latter number that actually separates Harper's stellar past three seasons (133 OPS+) from his 2015 National League Most Valuable Player Award-winning campaign (198 OPS+), when he slugged .801 inside the edges but .532 on other pitches.
   That gets to what Harper now has to overcome to produce the huge numbers his team will expect in 2019. With opponents so careful to make "pitcher's pitches" against him, he has to find a way to beat some of those, while pouncing on the mistakes he does get.
   This past season featured more of the latter than the former. See Harper's 13 home runs against pitches right down the middle, which led the Majors and accounted for about 38 percent of his season total. No other 30-homer hitter collected a higher percentage of his big flies against these middle-middle offerings.

Harper summed up the issues he faces when he spoke to reporters after finishing April with a whopping 38 walks in 29 games.
"On-base percentage is super important," Harper said, according to MASN. "Getting on base for the guys behind me, trying to have good at-bats and not expand the zone. It's definitely tough, but I've just got to keep doing it, keep trying to get on base and have good at-bats and wait for a mistake and not miss it."
Harper didn't walk that tightrope all year, though. Following a two-homer game on May 4, Harper hit .190/.317/.394 over a 61-game stretch heading into the All-Star break. He recovered emphatically in the second half (.300/.434/.538), in part by cutting down considerably on his chase rate.
It was the type of production that would make a pitcher justifiably timid of mounting a challenge in the strike zone. So as Harper heads toward 2019, perhaps in a new uniform, he will once again be dealing with that fear factor.