I'm sorry but how does a fresh out of college senior consultant gain such amazing experience?

I've been unfortunate enough to work with 3/4 of the big four (senior enough to at the table, not senior enough to call bullshit). Sales pitch is all partners; older people, lots of industry experience in relevant areas, great pitch. But, come time to deliver and an early 20-something shows up. So either its all covering your ass, or its just recycling reports from a shelf, either way there's no experience involved