Elevating is en vogue; everyone wants to do it and it seems like every hitter who does it can become a power hitter, especially with rumors about a new ball. There have been many examples of successful hitters of that mold: Daniel Murphy, Justin Turner and Jose Altuve, among others. Is there a limit to this? Could we see hitters with a 25% GB rate in the future? 20% 15%?
One thing that seems to cap this is BABIP. There is a pretty positive correlation of BABIP and GB rate, i.e. GB hitters tend to have a higher BABIP. That seems logical since FBs tend to have a lower average, and even if they are hits they often don’t count for BABIP as they are often home runs.
This table shows the relation of BABIP and GB rate between 2008 and 2017. You can see that BABIP does go down with lower GB rates, but wRC+ is actually better with lower GB rates. Still, you could see a point being reached where the lower BABIP eats up the advantages.
Average launch angle shows a similar picture:
|av. LA||<8||8 to 10||10 to 12||12 to 14||14 to 16||16 to 18||>18|
It seems that once you get past a certain launch angle or GB rate, a drop in BABIP is inevitable. However, an exception might be possible. I looked up guys with a lower than 35% GB rate and a FB rate of lower than 45%, and their BABIP was 0.304. Those guys were pretty rare between 2008 and 2017, but it is possible. You just need to get the ball off the ground and avoid both pop-ups and high outfield fly balls above 25 degrees. Not an easy thing to do, though, as the bat is a round object, and batted balls will always be distributed rather normally around the average LA, meaning that a higher average LA usually will mean more high outfield fly balls.
However, it is possible to imagine a super-hitter who has such good bat control that his band is very narrow. The best example of this might be Daniel Murphy, who managed to have a 34% GB rate with just a 40% FB rate (meaning a very high LD rate), and subsequently a very high (.345) BABIP over the last three years.
So we could indeed imagine a kind of “super Murphy” who hits 25% grounders with lower than 45% FBs. However, to date, we have not seen a guy sustaining such high LD rates; that guy would probably have to have superhuman bat control (which probably eliminates almost all >25% K rate guys). But with modern training methods, who knows what might happen.