Commits window shows commits timestamps as dates and for recent commits it is even worse - as "N days ago". You can see the very same date or even "N days ago" if you click on particular commit.
It is too ambiguous for serious dynamically maintained multi-branched projects.
I would suggest to show commit timestamps in the commits page and in the page for particular commit as date with minute granularity
PS: User can see exact commit time as UTC with up to second precision in "View raw commit", but this is too far down the user interface and by venturing outside of the BitBucket GUI (this is what "raw" actually asserts"