Bonuses are based on salary grade to start. Complanner has everything already set. So if your below a 27 grade your bonus will be minimal imo. I would say probably 1.5% of your base salary is a good ballpark for lower level employees based on the last few years payouts. If your 27 and 28 its anywhere from 3 to 8% depending on the year. I am not sure about director level but would assume its a little more, maybe 10%.
Your review score doesn't really affect bonuses that much. Its a formula based on the dept pool, individual rating and what they call entity rating which is likely the biggest factor. Which is how your overall large org did during the year.
Your mgr will likely be pretty equatable to everyone and they have to get everything reviewed up to your very high dept head. So any major distortion is questioned and discouraged.
Most directors and mgrs do not want that hassle. Your merit will not change much between a 3 to 4 or even to 5 .
If your 3 you may not get anything or something minimal like .5 to 1%. If your a 4 maybe 1.5 to 2%. A 5 which is very rare and discouraged, you maybe get 3% but only if your underpaid as it is. Otherwise your looking at 2.5%. Yes the really screw you over is the jest of it.