The only solution I've seen for phalanx is a very large shield value. That way fighting to the front and blocking arrows is great, sides somewhat weaker, while the back is much more vulnerable. Of course its hard to do that and stay consistent if you are trying to make stats follow some rules but sometimes the effect trumps the consistency- at least I think so. Not sure how the EB team will do it. I can think maybe HP could be used but HP and effective against armor are difficult to balance since they don't scale as well as other stats.

I've recently played around a bit with different stats helping test some mods and it can be interesting results. IE- 1 HP unit vs 2 HP is very stack difference and makes the rest of the states very secondary. However 2 to 3 HP or more improves that alot but does still make balancing difficult as to make the battles not take forever it requires some large offensive stats and is basically a huge amount of work since it starts to make armor and some other things relatively less important. So to model skirmishers without much armor or a shield requires 4 HP while high armor elites with high defense skill and a shield might get 3 HP and then the skirmishers don't die to some things so quickly but get them into melee with that elite unit and even with much lower stats they do a bit too well just because of the 1 extra HP.