Most CEOs of, say hospitals, didn’t work as nurses. Most oil company CEOs didn’t spend time as a roughneck. Hahn is bad at his job because he is a bad manager. If he were managing a Starbucks, it would be a disaster.
We all know that Hahn doesn’t know his core business: he can’t evaluate on-field talent, and he doesn’t know analytics. That’s not unusual. What’s unusual is that he has refused to hire the best people he can find who do know those things. Instead, he hires people who, if not his immediate friends, have similar backgrounds. Look at Haber, his chief assistant: top schools, sharp dresser and same skillset (or lack thereof). Where's the analytics department?
Hiring people who won’t show them up is a common trait of bad managers and Hahn scored big in that department. Billy Beane and Andrew Friedman weren’t afraid to hire Farhan Zaidi, e.g. Hahn hires Haber. Look who Hahn’s hired as field manager (when he’s been allowed to): not the sharpest knives in the drawer.
And, of course, he’s an excuse machine, another trait of bad managers.
I could go and on. He just needs to go.