Holding down Shift for more detail in your ability descriptions might not be a bad idea.

Remember when Riot tried making all the descriptions of Aatrox's abilities as basic as humanly possible, such as, "Aatrox dashes and then gets some AD" instead of adding any numbers? That surely was Aatrocious.

But that idea can be used in a better way!

My suggestion would be to show the combined numbers (base + ratios) when you hover the ability, but only show the actual base stats and ratios themselves when you hold shift. You know how many times you were trying to see how much damage an ability did, but you had to waste an extra two seconds of your life adding two or more numbers together? That IS the kind of simplicity we could use!