assistant head coaches and ratins

I have a good assistant head coach with my portland dynasty real team and of course because we're young of course we're struggling. Now, when i use the assistant head coach it says something about giving a small boost to to the team's passing and defensive ablitities. What does that mean, and what does an assistant head coach do?

In NBA Live 07 the Assistant Head Coach can manage various aspects such as scheduling the off-day events (practice sessions, media days, etc), adjusts the depth chart (which is not always desirable) and reports back about player improvement. They can also research league rumours.

but is there anything useful about them?

i got an A+ asst head coach with specialty in planning and all he's done is arrange schedules, like some scheduler.

wouldn't that job be done by someone with a C or D rating?

does the asst head coach actually had an impact to indiviaul player? and what's the use of researching rumor?

I would say it's definitely possible to get by without an A+ assistant. Researching rumours isn't essential but it can sometimes give you more of an indication that certain players are contemplating retirement or might be looking to sign somewhere.