Its nerfed/bugged
I did a small test, used my tier 4 helm with 14 crit and 1% reflect meta + adepts elixir so I have same spell damage as in my tier 6 helm that has 12 agility and 3% increased critical in it.
when I was wearing tier 4 helm(+adepts elixir) my crits were between
3714 - 3879
when I had tier 6 helm on(no adepts)my crits were between:
3715 - 3840
I unclicked any procs from my trinket so the data is more accurate.
here is a SS with combat log and stuff:
