The Nobel Prizes are awarded for conferring the greatest benefit to humankind. Showing how to use CRISPR as a genome editing tool (Doudna and Charpentier) confers much more benefit to humankind than "just" characterizing CRISPR (Mojica). I don't mean to trivialize Mojica's work, but at the end of the day if not for the later work of Doudna and Charpentier, Mojica's work on CRISPR would be unknown and irrelevant to 99.9999% of the world population.