Because I have eyes?
You have seen both play full games in person in college? I've seen both in high school (and Larrier in college). They were compatible talents in highs school based on their junior years. Now Moyer could develop at a faster pace, grow, etc. but as of the summer between their junior and senior years in high school they were/are comparable talents. Again, projecting a high schoolers leap into college is tricky. I would bet you would have expected more from top 50ish Joseph and he looked pretty overrated.