The way I've work it out to be is:

This is only for D1 (I don't feel like coming up with numbers for each circuit):

You can have a total of 150 members of say your drum corps.

You have to dedicate members to each of 4 categories:
Hornline,
Percussion,
Guard,
and Drum Majors.

There is a min and max in each division for total members. Let's go with 100 and 150 for Division 1 Drum Corps.

Within each section there is another min and max.
Hornline 50-80
Percussion 10-40
Color Guard 10-40
Drum Majors 2-5

Your rehearsals earn you a base score. This is what it would be like if you used the absolute minimum (72) performers (Note that you cannot actually have the minimum in each section). Having the max number of performers in a section earns you 106% of what the current system calculates your score to be (Notice you CANNOT have the max number of performers in each section). Each section affects a different set of scores a different amount. So take for example Visual GE. Since all 3 primary sections affect it, it is weighed accordingly. Color Guard boosts affect 50% of the Visual GE boost, Hornline 30%, and percussion 20%.

Hornline affects "Winds" (100%), "Music Ens" (60%), "Music GE" (60%), "Visual Performance" (40%), "Visual Ens" (40%), and "Visual GE"(30%);

Percussion affects "Percussion" (100%), "Music Ens" (40%), "Music GE (40%), "Visual Performance" (20%), "Visual Ens" (20%), and "Visual GE" (20%);

Color Guard affects "Color Guard" (100%), "Visual Performance" (40%), "Visual Ens" (40%), and "Visual GE" (50%);

So say, you have max hornline and min percussion, your total Music Ens bonus would be (.6*1.06+ .4*1.00) = 1.036. So if normally you would've earned 5.00 points in that caption, now you earn 5.18.

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Now the ticking aspect. Every time a tick is determined to have happened a .1 deduction is applied to the score after the number of performers calculation is added. Each and every member of your corps has a chance of ticking. For non-drum majors your ticking chance starts at 5% at the beginning of Competition Week 1. Week 2 it is 4.5%. Week 3 - 4%/. 4 - 3.5%. And Finals week every member of your corps has a 3% chance of ticking. So let's say you have 103 members in your corps including 3 drum majors. You then will have 100, .5% chances of ticking (determined by say a random number generator) on finals week.

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Now you may have noticed I've been ignoring drum majors. They're special.

Drum majors lower the tick probability. If you have the minimum of 2, then nothing happens. If you have 3, then your tick probability in the corps goes down to 4.5%-2.5%. 4 Drum majors lowers the tick probability to 4%-2%. 5 Lowers it to 3%-1%.

But Drum majors can also tick, but their ticks do not affect the score directly. They have the same 5%-3% (each) chance of ticking each show. When calculating ticks, the code would calculate the drum majors first. If any drum major ticks, it doubles all the other performers' chance of ticking. So let's say you have 5 drum majors and it's finals week. Each member of the corps has a 1% chance of ticking. But each drum major has a 3% chance of ticking. By some unfortunate luck, all 5 of your drum majors tick. Now instead of each member having a 1% chance of ticking, they have a 32% chance of ticking for EACH performer on the field (This would be a very bad day).

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And with the tick system comes a new set of Director Skills:

Unusually Cruel Punishments (As a director you and your staff are more creative whenever the kids mess up): 5 levels. 5 Director points each. Each level lowers the tick probability by .1% (so the minimum tick probability you can have going into finals would be .5%. This is the result of having 5 drum majors and maxed out punishments).

Inspirational Speeches/Hype (You and your staff are now better at preshow hype): 5 levels, 5 director points each. Each member of the corps has a chance to perform a perfect run. A perfect run results in a .1 boost to one of their their caption's score. (So a perfect run by a hornline member would add to the "Winds" score). If you have no points into this skill, you start at 0%. Each additional level adds 1%.

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Flaw.

Noone watches the drum major.

I really like it. However I still think the ticks should be worked by section (or something like groups of 5) not each performer.

It shouldn't be too hard to make it work individually. That way each and every member matters. But I can think of, with just my rudimentary knowledge of C++ how I would code each and every member to be calculated. Maybe because I'm still in the console, I'm missing some of the speed that factors into doing it here, but I can't see it being particularly hard.