TBC spell crit prediction while still casting - bug or not?

Im not sure if this is a bug or that's just how it worked back in the days, but i play a balance druid on warmane's outland tbc server, and my nature's grace buff pops up after i finish casting wrath, immediately, rather than when the spell hits the target and the crit actually happens. This is kind of frustrating. I dont know if there was any way to know for sure that you are gonna crit before the spell finishes casting back then but same thing happens with regrowth on any raid frame addon that tracks incoming heals.. they just know its gonna be a crit every time, bevore i finish the cast. Any opinions on this?
Reason why it negatively affects my dps is because when i spam wrath for some quick damage i want to use the procs for starfire, but because of the bug i need to jump and cancel the chained wrath from the spell queue rather than doing a wrath, doing a second cast, first one hits the boss and crits, then i see the buff while still casting so i can chain a starfire immediatly after second wrath is done.. am i the only class having this early crit display, is tit a server wide bug, or just a druid specific? I would make a ticket but not sure what to say in it.. game is not supposed to predict that ur spell is gonna crit before it hits..