Talking about the Assistant Manager, things might have changed a bit over the years - I often find following his advice about pressing high, attacking, playing through the middle (instead of flanks) and preserving the lead, if followed, makes the team perform better - but experience has taught me that in certain circumstances, he can be safely ignored. I've often had a 'whoa, don't do that!' feeling when he suggests things that I feel are incorrect for the opponent and match situation (usually in Associations matches - he's really useless there).
Give it a try - you may be surprised...
I'm still confused about him going on about full attack when losing and playing hard attack, attack bonus, up arrows on the midfield and strike force, and that weird one about being 'concrete in our actions' is a complete mystery - I've tried everything and still don't see what it's trying to tell me.