A very simple way to look at this is average HRs for the LEAGUE per year. We are about 10 games from the end of season 10 in Mattingly. Season started on 11/11, so the full year has been played under the new update. Here are the average HRs per team, league wide, for seasons 6 thru 9.
Season 6 218
Season 7 216
Season 8 211
Season 9 220
This year, season 10, the team average for HRs is 152! That's with 10 games . So it should end up at about 160 average HRs per team. The average team BA for seasons 6-9 was between .268 and .270. Season 10 average league BA is .267, so that's remained pretty much the same.
I know it's just one league and one season, but that's a 50 to 60 HR drop per team, on average. That's over 1900 less HRs, league wide, from season 9 to season 10! That's significant.