In the past couple of days i've started experiencing problems with the RPM using my career mode player (wrist spinner) solely with leg break deliveries. Sometimes it'll hit the max RPM but other times it's down about 300rpm. Half a season in with my player so his normal RPM is 1350 ish but this only seems to hit (with a 'perfect' rotation according to the meter) maybe once an over. This is the normal leg break option pointing northwest with the delivery stick. If I use the 'slow drift' or 'slow drift and flight' deliveries I get the full RPM every time, if I get the rotation correct.
I'm going to try it later on an exhibition match to see if I get the same problems, otherwise it might just be my career player. Saying that, it could just be a natural variation of the game, which is fairly realistic.
Having said all of this, I think the actual, discernable spin off the wicket is fairly consistent, so I'm not sure whether it's really making much difference apart from hitting me where it hurts (my RPM meter, or more accurately, my ego).