Well obviously people have more gear and its a lot more random than that. so lets assume you have 10% multistrike, thats 660 rating.
in those 25 attacks you would do 25750 damage. ~2.5 multistrikes would happen on average. could be 0, could be 1, could be 2, could be 3, could be 4,...
Now with that 660 rating that you geared towards multistrikes, we could put that gear towards vers. Thats 660 / 130 = 5.08%
So in those 25 attacks you would do 26450 damage. No RnG, it just happens.
So you are hoping on average RnG to do 25750 damage if you spend those gear points on multistrike. If you went verse, youd do 26450 damage no matter what.
Well what about crit!?!? lets assume you have 10% crit too.
So with 10% crit, and 10% multistrike damage.
you can expect 2.5 crits, and 2.5 multistrikes. Thats 3750 damage expected from crits, and 3250 damage expected from multistrikes. add that to the 20000 damage that happened without crits or multistrikes and you have 27000 damage.
Well, here you say "what if those multistrikes crit. thats the benefit im talking about. The 145% damage multistrike ive been lusting over!"
you have on average 2.5 multistrikes. at a 10% crit chance, .25 of those multistrikes are expected to crit. That means on average, you would need 10 multistrikes to get 1 of them to crit. Lets be generous and just say it happend. ill recalculate the damage portion expected from 1.5 normal multistrikes and assume one other one crit.
thats 1300, 650, and 1450. that equals 3400 damage. Add that all together and you have 27150 damage expected from those 25 attacks
Now lets do 5.08% vers damage with 10% crit chance over 25 attacks.
Thats 22.5 normal attacks for ~1051 each. and 2.5 crit attacks for ~1576. So add that up and its 23647 + 3940 = 27587 damage expected. No RnG involved from multistrikes. Just basic crit RnG.
So 10 times out of 10 the vers will do 27587 damage. If the multistrike geared person follows the expected amount of RnG then they will do 27150 damage. Now you are correct, you could get an extra multistrike. instead of 2.5 what if you got 3 or even 4? Well with 4 multistrikes where 1 crit(even though it statistically shouldnt) instead of 2.5 multistrikes where 1 crit, you would do 18500(non multistrikes, non crit) + 3900 (3 multistrikes), 1450(1 crit multistrike) , 3750(crit damage expected) = 27600 damage.
So if you got 4 multistrikes instead of the expected 2.5 and 1 crit, instead of the expected 1 crit out of 10, you could do more damage than a straight vers build. 4/2.5 = 1.6. so you would need 60% more multistrike procs then expected to do the same amount of damage as a straight vers build. This sound great, but for every time this happens, you would also go through a period where you did 60% less procs than expected. 60% less procs is = to 1 multistrike. So for everytime you get 4 multistrikes out of 25 attacks with a 10% multistrike chance, you are just as likely as scoring 1 multistrike out of 25 attacks.
Before you attack me for talking about .5 of a crit or of a multistrike, realize im doing average damage done. I could have expanded out to 50 or even 100 and those .5s would become 1 crit or 2 crit. Its all the same relative damage, im just focusing in on a smaller scale. Im aware you cant crit .5 times.