Rob Neyer, I believe, nails the reason for the drop in offense:
Maybe it’s really as simple as the umpires calling the strike zone that’s in the freaking rule book. More often, anyway.
This is based on a study by Dave Golebiewski that shows the umpires have expanded the vertical edges of the strike zone. One of the big complaints by pitchers in the 1990s was that they didn’t get the high strike. They’re getting that now, and a better low strike as well.
Note that there are many factors that go into this. Teams don’t seem to be building band-box stadiums as much as they did in the early 1990s. There is a natural cycle that goes back and forth between pitchers and hitters dominating. Drug use and equipment all play apart (maybe hitters need greenies more than we know). I like offense where it is right now, not too much, not too little, so maybe baseball can hold it steady for a while.
(Note football changes the rules to keep games at an average of 42 points. They move the hash marks, move the goal posts to encourage or discourage field goals, play with the rules about tackling the quarter back, etc.)
I think 3 things have all played a part in the drop of offense:
1. The decline of PEDs.
2. The renewed emphasis on defense/improving defensive metrics.
3. As you now suggest, better strike calling on the part of umpires.
I think certainly there is an expanded strike zone which hurts hitters.
Not buying the stadium theory as it can not account for all of the drop and offense is down even in those hitters parks.
Can’t rule out the ball. MLB has a lot of pressure to show Congress their testing program works. Hard to do when no big names get caught and suspended and players are bigger than ever.
This theory that PED’s are down and are the reason for offense being down does not hold water. Pitchers were using PED’s as much as hitters.
According to Balco founder Conte, he believes players are still using PED’s but have switched to short acting testosterone which leaves the body in hrs. They can take them during or after the game when they know there will be no testing, and by the time they come to the park the next day the testosterone is cleared from their body having helped their muscles recover from the game.
During the offseason, I am sure players can use longer acting steroids without being tested. How does a collector get you if you spend the offseason in the DR or at the API in Arizona. Those who are not using, or have completed their cycles by a couple of weeks, can stay home and can be tested and will always be negative.
Better defensive players can not be the reason since no matter how good a fielder you are, you can not defend against the HR.