Bregman is doing ok with the exit velos and hard hit%, he's just not pulling hard hit balls in the air for HR like he has in his other years. His flyball% and GB/FB ratio are the worst of his career, so he's hitting more balls on the ground then ever and more liners rather than FB. Hopefully he gets his power stroke down soon.
The stats that compare HR by venue don't say the ballpark is the issue.