Imagine you have a pool of candidates. One has a proven track record. Five are equally good as him but lack the track record. Four are duds. Lacking domain kno

Imagine you have a pool of candidates. One has a proven track record. Five are equally good as him but lack the track record. Four are duds. Lacking domain knowledge yourself you can't tell the good from the duds, so you go with the guy with the track record.