The breakpoint add significant value to haste around 20%, but if you follow the reforge plots there is still a trend of increasing DPS beyond that for around 1k-1.1k haste, or around 30%, before haste starts to be a DPS loss vs. mastery.That seems odd to me, at least from a usable standpoint. I thought the lion's share of the value of haste comes from the boost heroes get at breakpoints.Warsong is always better than bleeding hollow, even for the mythic profile (took out the legendary from it). The enchants are pretty much always haste enchants, even in BiS.
So relying on a proc to benefit a proc of a proc, seems a bit off. While I get more casts means more procs, the fact there are breakpoints means static haste giving a bonus attack is what gives it the extra oomph.
Or does the
There is also the confounding factor of pet delay. Pet delay removes some of the strength of the breakpoint and distributes it into the haste ratings beyond it (because more haste seems to reduce pet delay). So having haste beyond the breakpoint is a DPS gain in that regard too.
In regards to your "proc benefiting a proc" thing, the sim models both procs accurately, and so the results clearly show that the additional haste, even though it's a proc, results in an increase in pets/petuptime to be worth to DPS that the mastery enchant would afford. Mastery does nothing for the pets; so any time they are up with the mastery enchant, it has lost value vs. the potential bonus attacking during the haste proc, and the potential extra pet summons.