Pretty easy KV,

That is saying their is a 1 in 40 chance your system could drop 25.4% POT from it's current POT, whatever your POT, as a general guide.

Now sub the green 28 (in the middle) with green 22.9.
It should now say that your system of 18% SR after 400 bets could
possibly be 20.7% POT worse off than what it is, this is a 1 in 20 chance
(or 5% chance) of happening.

Again, sub the 28 with the green 17.4.
Now with fair accuracy you system (18% SR, 400 bets) could fall 15.8% POT
from it's current POT, this is a 10% chance of happening.

Personally, I'll stick with the 17.4, so if my system has had 500 bets,
20% S/R, 39% POT then there is a 10% chance my system may fall to
a permanent POT% of 26.2%. Of course call fall lower, less chance though.

But with the table above I would know that my system has a better than even chance (actually 40% chance ) of permanently hovering around the 31 - 47% POT range.

Kapiche, it's just a guide. That is all.