Sano is 2017's hardest-hitting slugger

Miguel Sanó leads all Major League players with the highest percentage of hard-hit batted balls, which is really impressive. He leads the Majors in the highest percentage of productive batted balls, which is also really impressive. If those sound like the same thing, they're not, not exactly, and we'll explain why in a minute. But for now, just note that the Twins' third baseman, who turned 24 last week, is proving himself to be arguably baseball's most impressive masher. It's a great sign for a surprisingly entertaining Minnesota team.
Let's talk about how Sano has crushed his batted balls, but first let's talk about what "hard hit" actually means, because there's a few ways to define that. For years, a hard-hit ball was one that simply looked like it was hit hard. As we began to be able to measure exit velocity, "100 mph or higher" seemed like a nice breakpoint, mainly because 100 is a nice round number that sounds impressive. But as data began to accumulate and we were able to see what the numbers actually led to, it became clear that "95 mph or higher" was the appropriate floor for a hard-hit ball.

You can see why in the image above, right? ("wOBA" is Weighted On-base Average, which is very similar to traditional OBP except it gives more weight to extra-base hits than walks and singles, instead of giving equal credit to all times on base. The 2017 Major League average wOBA on batted balls is .368.) For the most part, if you're hitting the ball more softly than 90 mph, it doesn't really matter that much how much lower, which is part of why this is a better measure than "average" exit velocity.
Between 95 mph and 105 mph it matters a lot, and it tails off after that, as hitters trade loft for velocity. Or if you want it more simply, in 2016-17, batters have hit .541 with a 1.074 slugging when they hit the ball 95 mph or harder, and just .218 with a .255 slugging when they hit the ball 94 mph or lower. While it's obviously important to combine that with a strong launch angle -- more on that in a second -- the more often you can hit the ball 95 mph or harder, the better off you'll be.

Entering play on Tuesday, Sano's doing it more than anyone, by an absolutely absurd amount, 10 percentage points above the next-best hitter, who just happens to be one of the best sluggers who ever lived.
Highest percentage of batted balls hit 95 mph or harder in 2017
68.3 percent -- Sano, Twins
58.9 percent -- Miguel Cabrera, Tigers
58.0 percent -- Khris Davis, A's
57.6 percent -- Joey Gallo, Rangers
55.5 percent -- Nick Castellanos, Tigers
54.6 percent -- Manny Machado, Orioles
52.9 percent -- Ryan Zimmerman, Nationals
51.3 percent -- Aaron Judge, Yankees
51.3 percent -- Matt Carpenter, Cardinals
51.0 percent -- Justin Bour, Marlins
Minimum 50 balls in play. MLB average -- 33.5 percent
That's a nice list. So we've established that hitting the ball over 95 mph is good, and that Sano does it more than anyone. Great, right? But as we've also learned, it's also about getting the ball off the ground. Remember before when we said that in 2016-17, the Majors have hit .541 with a 1.074 slugging when the ball is hit 95 mph or harder? That's .615 with a 1.315 slugging when it was hit that hard above the ground… and just .315 with a .337 slugging when it wasn't.

It's a massive difference, so we need to account for angle as well as velocity. After all, we all remember hearing this offseason about how Zimmerman had a poor 2016 season despite above-average exit velocity, because he hit the ball on the ground too often, and part of his 2017 resurgence has been getting those hard-hit balls elevated for maximum damage. To that end, we've identified six types of batted-ball contact, three of which are good for the pitcher (weakly hit, popups or topped into the ground), and three of which are good for the hitter, including barrels. The three "poor contact" types have a Major League average of .139 this year, while the the three "hard contact" types have result in an average of .652.
Sano is leading baseball in that, too.
Highest percentage of "productive" batted balls in 2017
58.7 percent -- Sano, Twins
55.0 percent -- Carpenter, Cardinals
53.9 percent -- Judge, Yankees
52.8 percent -- René Rivera, Mets
52.5 percent -- Justin Smoak, Blue Jays
51.9 percent -- Zimmerman, Nationals
51.6 percent -- Stephen Piscotty, Cardinals
51.5 percent -- Castellanos, Tigers
51.2 percent -- Matt Kemp, Braves
51.2 percent -- Yonder Alonso, A's
Minimum 50 balls in play. MLB average -- 36.6 percent
As you'd expect, there's some crossover, but not completely so. After all, as Zimmerman showed, you can have a ball hit at 95 mph or harder that's not "productive." You can have a "productive" ball that isn't hit hard, if it's a well-placed bloop. Sano isn't crushing these hard-hit balls on the ground. He's putting them where they matter, generally the bleacher seats.
Hitting the ball hard, as we've learned, is a skill. Sluggers like Sano and Giancarlo Stanton have it; guys like Dee Gordon and Billy Hamilton do not. That being the case, it's got a very strong year-to-year correlation -- that is, if you do it well one year, you're pretty likely to do it again the next year, barring injury or some other issue. 

 In 2016, 391 hitters had at least 100 balls in play, and Sano's percentage of balls hit over 95 mph was sixth highest. One would think there wouldn't really be anywhere else to go from there. But not only has Sano increased his hard-hit percentage, he's done so by more than anyone -- despite the lofty start. 
Biggest increase in percentage of batted balls hit 95 mph or harder in 2016-17
18.6 percent -- Sano, Twins
18.5 percent -- Taylor Motter, Mariners
16.8 percent -- Castellanos, Tigers
15.2 percent -- Lonnie Chisenhall, Indians
15.1 percent -- Jed Lowrie, A's
14.3 percent -- Aaron Altherr, Phillies
13.2 percent -- Caleb Joseph, Orioles
13.0 percent -- Trea Turner, Nationals
10.8 percent -- Machado, Orioles
10.5 percent -- Eugenio Suárez, Reds 
That's a list with some breakouts, like Motter, Altherr and Suarez. It's got some veterans having nice starts, like Lowrie and Chisenhall. But atop the entire list is Sano. He was already elite at this, and he's improved. Sure, Sano strikes out too much. When you crush like this, however, it really doesn't matter. As we've been expecting for years, Sano has arrived. He's not a future star. He's just a star right now.