Knowing things isn't really the tip off of a good programmer. Put them in a foreign environment, with a foreign language/api/framework/application/etc and with

Knowing things isn't really the tip off of a good programmer. Put them in a foreign environment, with a foreign language/api/framework/application/etc and within a short learning curve they will find solutions to problems 1) you didn't know you had, or 2) you had long since given up on finding a better solution to. If you can replace the programmer with books (and time to read them), they can't be that valuable. You don't pay one person 5 times market rate if 5 people at market rate can do their job. You pay someone for the concentration of talent.