This is a difficult question.
"We expect good things from you" means "We think it is likely that you will give us good things."
"We expect good things of you" means "You are required, considering your position/talent to reach certain standards of excellence, to carry out certain duties, imposed on you by that very position/talent. You owe it to us."
Here, "...what was expected of them" means "the professional, ethical and fiduciary duties that they were required to have performed by virtue of being lawyers." "...expected from them" is to do with required standards.
"...what was expected from them" would refer to concrete products such as reports and phone calls, or acts such as kind words, or an attribute such as an attitude.