It is hard to tell what crit talents/runes are not being applied but if you look at the many logs on WCL of fights greater than 2min (because short fights cause combustion to mask this issue), frostfire bolt crit chance is much lower than it should be.
Raid buffed with the burnout rune, mages should easily have 35% or more critical strike chance. Yet, Frostfire crit % throughout the fight is under 20%, and I see logs as low as 8% despite a high amount of casts.
I suspect that the burn out rune (15% crit) is not being applied to frostfire bolt, and potentially crit chance from fire and frost talents.
There is also reports that frostfire bolt doesn’t get extra crit from the shatter talent in frost, but I don’t play that spec so can’t confirm.
Combustion seems to work to some degree though!
Thanks!