When the Phillies and Diamondbacks combined to set a single-game MLB record for home runs with 13 combined, it illustrated a more extensive development in the league. Home runs are being hit more often than ever before, even more than the last few years when that was said.
At the end of May, Jayson Stark of the Athletic [subscription required] wrote that the league is on pace to hit 6,516 home runs. This would be about 1,000 more than last year and 2,500 more than five years ago.
This trend extends to the Triple-A Pacific Coast League, which switched to using major-league balls this year.