The Math for diminishing returns for critical strike:
For ease of use, all other things are equal.
For each 1% chance to critically strike an enemy, it provides a static increase to the statistical dps a character will do. It's important to note the word "static" in this formula. This is to say 1% increase in crit will provide a character that does 1000 dps an extra 10 dps. Now the character is doing 1010 dps (I'm using easy math for this, nothing too complicated). Now 10 dps over 1000 is a 1% increase.
Now the player chooses to increase crit another 1%. Now the character is doing 1020 dps. But the increase of 10 dps from 1010 dps to 1020 dps is NOT a 1% increase, it is slightly less than 1%. Over time and along the curve, if you do you f(x) limit as crit approaches 100% (or 1 in the math terms), you'll see the curve show diminishing returns over time and how valuable crit is at certain points along the curve.
Power as a stat suffers from the same diminishing returns, but not subject to the RNG detractor that crit is.
So what you have to do is go along the curve to find the value per point of increase of each stat: surge, power, and crit. And balance them accordingly to pick the best gear that has the largest increase of value per point provided along each curve.
I would be willing to do the actual analysis as I have crystal ball on my computer if it is of serious interest to the player base.
I wasn't referring to the math behind DR. I was asking for whatever "math" he used to determine that 25% crit total was the end of crit's usefulness at which point you stack power to the sky. Obviously he didn't actually have any mathematical evidence to support this so he just kept babbling on and I left out of frustration.