The biggest story right now in baseball is the move toward hitting fly balls, and it's in full effect, because barely a day goes by without one hitter or another talking about elevating or launch angle or simply getting the ball off the ground. You know the stories by now, how such sluggers as Josh Donaldson, J.D. Martinez, Daniel Murphy and Justin Turner focused on hitting the ball hard in the air and turned themselves from role players (or less) into stars. You've seen what happened to Ryan Zimmerman this year when he elevated his hard-hit balls, though he insists it wasn't on purpose. You've seen Yonder Alonsotalk about trying it this spring and suddenly turn himself into a star.
For so many players, elevating has become a path to great success, and we fully believe it's a contributing factor to the surge in home runs we've seen over the past few years. ("If I fly out four times, I had a great night, because I didn't hit a ground ball," said Turner.) So if it can lead to such productive outcomes, everyone should do it, right?
Well, no, actually. Quite the opposite, because few things in baseball are "one size fits all," and neither is this.
As it often does, it comes back to exit velocity. Hitting the ball hard in the air is great if you can smash it like Donaldson or Martinez can; it's a lot less useful if you're a relatively underpowered speedster like Jarrod Dyson or Dee Gordon. As the data shows, simply elevating doesn't lead to any notable increase in success across the board. It's those hitters who have the ability to hit it hard in the air who can really benefit from this change in strategy. (And it is a change, based on all the anecdotal evidence of hitting coaches at all levels who preach the value of trying for grounders.)

So the question isn't just about elevating, it's about elevating with power. And while we're here, why are we focusing on "fly balls," anyway? If line drives are valuable -- and they are -- then we shouldn't be excluding them here, especially in the cases of players who turned their grounders into line drives, not fly balls. If anything, it's less about "more fly balls" and more about "fewer grounders," at least for those who can hit in the air with enough power. That's where the value is.
As usual, Joey Votto nailed the idea.
"The consensus among all the hitters I've spoken to, and hitting people I've spoken to," said Votto to Travis Sawchik of FanGraphs recently, "is ground balls are bad, fly balls are good, line drives are good."
Well put. So since the "Anti-Grounder Revolution" seems a little clunky, let's rename this the "Air Ball Revolution," as Murphy is fond of calling it, and let's explain why it doesn't apply to everyone.
Instead of calling things "grounders," "liners" and "flies," we'll look at batted balls above 10 degrees of launch angle, which is the low end of where line drives begin, and call those our "air balls." That includes popups, which are bad for the hitter. If you were to look at the 300 hitters with at least 50 batted balls in both 2016 and '17, ignore exit velocity, and find only the ones who made the biggest strides in hitting the ball in the air this season -- or, put another way, hit fewer grounders this year -- you will find some very mixed results.

Biggest increase in percentage of "air balls" (10 degrees or higher) in 2016-17
+25.5 percent -- Alex Avila, Tigers (+.115 wOBA)
+19.5 percent -- John Jaso, Pirates (-.027)
+18.3 percent -- Alonso, A's (+.143)
+14.4 percent -- Miguel Montero, Cubs (+.045)
+14.2 percent -- Josh Reddick, Astros (-.007)
+13.5 percent -- Travis d'Arnaud, Mets (+.049)
+12.5 percent -- Miguel Rojas, Marlins (+.082)
+12.4 percent -- Christian Vazquez, Red Sox (+.100)
+12.1 percent -- Brett Gardner, Yankees (+.053)
+11.8 percent -- Ryan Rua, Rangers (-.034)
(*wOBA is Weighted On-Base Average, which is very similar to On-Base Percentage except it gives increasingly more credit to extra-base hits as opposed to treating every time on base equally, as OBP does. The 2017 Major League average wOBA is .318.)
That's ... a real weird list, right? Avila and Alonso have each been crushing the ball, and Gardner has shown a newfound ability to smash in the air. But Jaso, at .231/.318/.385, is having his worst year since 2011. Rua has lost more than 30 points of slugging. Reddick is basically having the same year as last year. This is a list of elevators, but it's not a list of sudden stars. Again, elevating by itself is not a key to success -- elevating with velocity is.
Let's look at that list again, except this time we'll include exit velocity in the form of hard-hit balls above 10 degrees. We've defined a "hard-hit ball" as one being 95 mph or higher, because that's where the evidence provides a very clear break point. Since 2015, Major League hitters have batted .540 with a 1.058 slugging (.667 wOBA) at 95 mph or above, and .218 with a .255 slugging (.206 wOBA) at 94 mph or below. It matters a lot more to get above 95 mph than it does how far over or under it you are. 

At 95 mph or higher, and at 10 degrees or higher, the Majors hit .607 with a 1.547 slugging percentage (.872 wOBA) -- it's where 96.5 percent of all home runs live, and the real damage zone is centered around 28 degrees. If you're hunting for success, this is where you want to live.
Biggest increase in percentage of "air balls" (10 degrees or higher) at 95 mph+ in 2016-17
+23.9 percent -- Avila, Tigers (+.115 wOBA)
+15.4 percent -- Lonnie Chisenhall, Indians (+.031)
+13.5 percent -- Alonso, A's (+.143)
+12.9 percent -- Scott Schebler, Reds (+.024)
+12.5 percent -- Greg Garcia, Cardinals (-.031)
+12.1 percent -- Martinez, Tigers (+.094)
+11.8 percent -- Zimmerman, Nationals (+.193)
+11.7 percent -- Paul Goldschmidt, D-backs (+.036)
+11.6 percent -- James McCann, Tigers (+.031)
+11.6 percent -- Francisco Lindor, Indians (+.011)

Now we're getting somewhere, because every hitter on this list has been above average this year, and nine have been better than last year. Avila, Alonso and Zimmerman have had huge breakout years. Schebler is tied with Zimmerman for the most homers in the National League, at 16. In the next group of 10 are Gardner, Jake Marisnick, Colby Rasmus and Logan Morrison, all having big power surges. At the bottom of this list are four hitters who have lost at least 10 percentage points of hard-hit air balls (Lucroy, Luis Valbuena, Adam Rosales and Troy Tulowitzki) and have each struggled this year.
There's one more step we need to take, and that's to account for strikeouts. If a hitter elevates for power and strikes out more because of it, there's a line where the elevation no longer is worth it. While strikeouts by themselves don't matter -- note that Marisnick and Matthew Holliday have both whiffed far more than in 2016 but have been far more valuable overall while doing so because they hit the ball hard in the air -- if they don't come with a corresponding increase in production, then the tradeoff doesn't make sense.
If we look at all of the 300 hitters in our sample, the trend among those who added hard-hit air balls is clearly toward more overall production, regardless of strikeouts.

And the trend among those who added more softly hit air balls is clearly in the opposite direction.

So no, not every hitter should try to elevate. It might be a revolution, but it's a very targeted one. If you can hit the ball hard in the air, fantastic. If you can't, it might not be for you.