>This is saying that people in congressional leadership positions do 47% better than other members of Congress.

It's even more damning than that I think.

>we find that lawmakers who later ascend to leadership positions perform similarly to matched peers beforehand but outperform them by 47 percentage points annually after ascension.

The same person makes more after being put in a leadership position than before. That essentially removes any possibility of 'well maybe they're just more knowledgable and that's why they're in leadership.'