How can baseball get more balls in play? As strikeouts and home runs continue to rise, the question of how the sport can get more batted balls in the field of play was one of the main topics posed to the "Changing State of Sabermetrics" panel at the 47th annual Society for American Baseball Research (SABR) convention in New York.
First, some facts. Strikeouts are up, as 2017's 21.6 percent strikeout rate would be the 12th straight season that whiffs have either held steady or increased. It's undeniable that home runs are up, as we'll likely see the sport hit the 3,000th homer of the season tonight, weeks before the All-Star break, while we saw just 4,186 in the entirety of the 2014 season.

Now, whether or not that's actually good or bad is open to your interpretation. Home runs, of course, can be extremely exciting to watch. Strikeouts may not be, though as we noted recently, there's not really any badge of honor to be handed out for weakly tapping out to second as opposed to swinging and missing. 
But let's say you do want to get more balls in play, regardless of what other effects it brings with it. How would you do that? The panel, comprised of myself, Joel Sherman of the New York Post, former Major Leaguer Mark DeRosa, SABR president Vince Gennaro (and hosted by MLB Network's Brian Kenny) had some ideas.
Change the mound.
There's a few reasons for the increase in strikeouts, but there's two that really stand out. The first is that strikeouts and low batting averages no longer carry the stigma they once did, and that's not likely to change. (Houston's Jake Marisnick, for example, is striking out a career-high 33 percent of the time, but he's also gone from hitting .209/.257/.331 to hitting .256/.336/.529; though he's whiffing more, he's far more valuable overall.)
But the second item is simply increased velocity. In 2008, the average fastball was 91.8 mph. In 2017, that's 93.6 mph. It used to be impressive to see a pitcher touch 95 mph, and now every team has multiple guys who can do so. It's extremely unlikely that's going to change, and it'll probably keep increasing for a few years. If velocity is too dominant, might there come a day where we'll need to make it a little harder for pitchers to throw so hard?

Moving the mound back from its current 60 feet, 6 inches isn't going to happen; that's been the standard since basically the beginning of the sport, and that would radically change the symmetry of the field. But changing the height of the mound has some precedent, as after 1968's "Year of the Pitcher," the height was lowered from 15 inches to its current 10, to disadvantage the pitcher. We're probably not there yet. It's not totally out of the question, however.
Change the rules of bullpen usage.
If we want to try to limit velocity without changing the physical field of play, a good way to do that would be to place constraints on how managers can use their bullpens. A big part of the velocity increase, aside from bigger and stronger players, is simply due to the fact that an endless stream of relievers can come in and throw as hard as they can for 15-20 pitches, knowing they don't need to pace themselves for later innings. Forcing relievers to remain in the game for at least three hitters (or whatever the proper number would be) would at least add some amount of necessity to think beyond just the current hitter.

There would be other benefits to this, too: Managers would find it a little more difficult to get the platoon advantage on the mound, which would benefit hitters. And, this might lead to fewer mid-inning pitching changes, would could also help pace-of-play concerns.
Restrict the shift.
The shift, of course, is everywhere. In 2010, the shift was in use on just over 3,000 balls in play. So far this year, the shift has been used against more than 17,000 balls in play. The shift itself doesn't prevent contact, but what it does do is to change the approach of hitters who are constantly getting beat by it. Why ground out into the shift when you could try to hit over it?

"You don't beat the shift by hitting around it or through it, you beat the shift by hitting over it," Justin Turner told MLB.com this spring when asked about his hitting approach. "Ground balls up the middle, in general, just aren't going through like they used to be," said Jedd Gyorko of the Cardinals. "So there's a lot more room hitting the ball in the air."
Of course, doing that comes with a cost. Trying to hit homers, or trying to hit it hard in the air, knowing that a grounder won't do you any good, comes with a cost. That cost is generally lowered contact, so outlawing the shift might allow some of these hitters to make more contact. Generally, we're against preventing innovation in the game, but there's at least something behind this idea.
Change the composition of the ball.
The potential of minor changes to the ball fueling the home run surge has been a hot topic for some time, and countless scientific studies have gone back and forth on how much of an impact any changes might have had. Either way, we know this much: The best way to get more balls in play is to get fewer strikeouts and fewer homers. (Again, whether you want that is up to you.)
So, suggested DeRosa, why not intentionally make the ball easier to contact? Changes to the seams could make it harder for pitchers to add movement, and less movement would make it easier for hitters to make contact. A radical change, to be sure.
There's other ideas, of course, ranging from changes to the strike zone to changes to the bat to some undiscovered way to simply make hitters wantto strike out less. There's no right or wrong answer, not yet. The discussion continues.