The walk-off home run Josh Harrison hit to spoil Rich Hill's no-hitter on Wednesday wasn't the hardest-hit ball of the game. It wasn't the farthest-hit ball of the game. It wasn't the ball most likely to be a hit, based on our most advanced metrics that combine exit velocity and launch angle. It wasn't among the top 20balls of the game most likely to be a hit, believe it or not.
But it didn't need to be. A ball that even Harrison himself knew he hadn't hit perfectly -- "I knew I didn't get it all, but I knew I got enough," he said after the game -- won the game in perhaps the most Harrison way possible. No one gets as many unlikely home runs as Harrison does; it's practically a skill in and of itself that he's ridden to a career-high 16 homers and a second All-Star game appearance.
We mean that in every way. No one hits homers like Harrison does. Since 2015, there have been 275 players who have hit at least 20 dingers, and Harrison's average home run distance of 382 feet is tied for second lowest -- ahead of only Didi Gregorius's access to the short porch in Yankee Stadium. His expected batting average of .445 on home runs ranks 275th among those 275 players.
Expected Batting Average on home runs from 2015-17

1. .870 -- Giancarlo Stanton, Marlins
   
2. .869 -- Aaron Judge, Yankees
   
3. .865 -- Trey Mancini, Orioles
   Major League average -- .711
   
4. .502 -- Ian Kinsler, Tigers
   
5. .492 -- Zack Cozart, Reds
   
6. .445 -- Josh Harrison, Pirates
   Obviously, the actual batting average on a home run is 1.000. Every home run is a hit. But we're looking at the likely outcomes based on the combinations of exit velocity and launch angle, to account for the fact that real-world outcomes can be affected by parks and defense. Dodgers outfielder Curtis Granderson, for example, came within inches of making a fantastic catch on Harrison's homer. Whether Granderson did (out) or didn't (home run) make the catch was out of Harrison's control, so we credit him for the skill shown in making contact.
   What that .445 means is that cumulatively, the types of home runs Harrison hits shouldn't (based on exit velocity and launch angle) even be hits more than half the time. Wednesday's home run was hit at 94 mph; only 2.4 percent of homers since 2015 have been hit that softly or lower. The combination of of 94 mph and 33 degrees launch angle has a Hit Probability of just 16 percent. It's turned into a home run just nine percent of the time, as you can see in this spray chart.

But while it sounds like we're saying that Harrison isn't earning his home runs, we're not suggesting that at all. Crushed or not, a ball in the seats counts just the same as any 490-foot blast by Judge, and the point here is that Harrison has found a way to use his batted-ball skills effectively.
If Harrison had hit that ball to center field, it's an out. But take a look at the homer again, specifically where it was hit.

Now look at Harrison's home run off Adam Wainwright last week, hit at a similarly low 92.2 mph exit velocity and a projected 346 feet.

... and also the one he hit last year off Dan Straily, then with the Reds.

Notice a pattern? Take a look again at where the home run off Hill landed:

Now, take a look at Harrison's home runs hit in Pittsburgh over the past three seasons. See the cluster of dingers right down the left-field line? It's one of the shorter potential homer spots in the Majors.

At 325 feet, PNC park's left-field fence is tied for the fourth shortest in baseball, and it comes without the 37-foot wall that Boston (one of the three shorter) features. It's an extremely tempting target for a hitter without elite power, and whether it's conscious or not, Harrison is hitting the ball to his pull side more often -- and it corresponds to his overall success.
Harrison's pull percentage and OPS+ from 2014-17
2014 -- 45 percent / 133 OPS+
2015 -- 36 percent / 97 OPS+
2016 -- 41 percent / 86 OPS+
2017 -- 44 percent / 106 OPS+
Why not? If you have a short porch, go for it. Impressive home run distances are fun, yet hitting long homers doesn't put any more runs on the board than getting the ball inches over the wall. A home run is a home run, no matter how you get there.
You can feel bad for Hill, of course, losing on a home run like this, though don't feel that badly for him. After all, it took a great play from Chase Utley to keep the perfect game alive in the first place, and then he ran into perhaps the most likely Pirate to break up history on a night where Hill wasn't allowing hard contact. Harrison, as it turns out, doesn't require hard contact to make an impact -- but he does make an impact.