Well that's the whole point of having a plan to compare results against
Maybe your avg bet is lower because of some "except" stuff - fear of putting big bet out when called for perhaps. Maybe it's because you have had a disproportionate number of hands that have not yet called for a big bet yet but you've been betting perfectly. So that could explain it.
At least it gets one thinking as to why deviations are occurring - bad counting? bad betting? bad luck?. Am I really playing the game I simmed (pen etc)?
Maybe with the info that CVBJ or whatever it is is giving you, it's possible you can pinpoint stuff even more. Like can it isolate avg bet at each TC? Are the proportions of TC's that are actually occuring in line with the sim's frequencies? Stuff like that you probably would never know in real life at a casino so take advantage of it.
It may even be possible, with software like that, to retroactively figure out what results would have been without the mistakes.
For better or worse, at least things aren't in a totally meaningless vaccuum anymore.
I mean, really, the best thing you could find out, even if it seems like the worst thing, is that you find out you need more practice. To me that's alot better than spending a lifetime cursing the incredibly unlucky fate a perfect counter, that we all think we are, can have lol.
By all means, if your "except" stuff occurs often enough and consistently enough and you know it, sim that and see what to expect! Pretty much exactly why we get sim software. Maybe you just find out that that's a plan you really wouldn't have chosen to play, especially compared to the one you started off with. If so, even if not, maybe you learned something and know a little more than you did before.
Edited to add - you're right 8-900 hands isn't alot but as you can see it's enough to get you thinking anyway. Perhaps resolving even more to stick to the plan, etc. Analyze the next 900 as if they were the first 900 etc.