Rather you fall back on your level of training. A great example of this happened on the PTS test last Friday. For one part of the test, each side alternated defending Chillwind Manor in Eataine. With friendly collision turned off, defending was much more difficult. I don't think either side really knew how to efficiently defend the BO without it.
In PK, we'd let the attackers in the BO a little bit and kill them as they come in. The attacker's advance would be slowed as they got caught on each other and they would die to our damage as they came in. Sure they might outnumber us 4 to 1, but when we have a warband and we only engage half a warband at a time as they push in, it's quite easy to win.
Defense of the BO failed hard on both sides. Even the outnumbered side managed to grab the BO eventually.
Assaulting the defended position did not change at all. I instantly knew how to beat that from my past experience. I told my side we should hold to morale 3, have a couple tanks go in and drop Challenge and Distracting Bellow, followed by everyone else to mop up. With incoming damage dropped to 35% of normal, it was nothing to get everyone in quickly and safely. The enemy front line disintegrated within seconds on the morale dump.
I'm not yet sure how to defend such a position without friendly collision. It will likely involve having to be much more aggressive though. Once I figure out something, I'll test it and, if it works, train the rest of my alliance on it.
I'm starting to think tanks in WAR are a lot like the offensive/defensive lines in American football at least in oRvR. If your big guys beat up their big guys, chances are pretty good you're going to win.