We've seen enough to say what Nick Mullens does better than Jimmy Garoppolo.
That's not to say Mullens is better than Garoppolo -- he's not. But Mullens clearly does certain things better than him:
1. Mullens has more composure and confidence than Garoppolo right now. Garoppolo had those things in the past, but he has torn an ACL and lost a Super Bowl -- there's a dark cloud over his head. And about once every game, he goes through a period in which he has the yips. He'll seem tentative and indecisive -- call it Bad Jimmy. Mullens hasn't played long enough to get the yips. He hasn't suffered a major injury or a major defeat.
2. Mullens processes information quicker than Garoppolo. Mullens is a computer. He gets through his reads quickly and efficiently. That's what Shanahan means when he says Mullens never hesitates. Shanahan hasn't said that about Garoppolo, because Garoppolo is not a computer. He plays on instinct and feel.
3. Mullens understands his physical limitations better than Garoppolo. Garoppolo is the guy who lowered his shoulder and wanted to hit the defender in Kansas City rather than run out of bounds, and that's when he tore his ACL. Mullens would have ran out of bounds. Garoppolo likes to adlib and showcase his athleticism while Mullens tends to stick to the script and hide his athletic shortcomings.
Mullens played college at Southern Miss and frequently faced defenses that outmatched his offensive supporting cast. So he has experience protecting himself and masking his lack of athleticism. Garoppolo played college at Eastern Illinois, the best program in a small division. Garoppolo was the most athletic player on the field in college -- he could run defenders over if he wanted now. Not anymore. And now when he scrambles, it seems the speed of the NFL game still surprises him.
Of course, Garoppolo does many things better than Mullens. Stay tuned for that list.