Operations seems to only prioritise absolute casualties when it comes to whether an attack was strong, weak or efficient, in terms of overall score this will take into account all losses the attacking team took in terms of both battalions and tickets, but for sectors will only take into account individual battalion ticket losses. Emphasis on seemingly, it's also possible it may take into account speed but hard to say without anything official to go on.
Further the game will be more rewarding of an attacking team who zerg through the entire operation with minimal casualties, for individual sectors the attack rating will reset upon defeated battalion this means if you push through with the behemoth immediately and take the sector after losing a battalion there (whether it was all tickets on one sector or an attrition of tickets up to the sector) you will be awarded a strong attack for that sector and the defenders - despite holding an entire battalion off in said sector, will receive a weak defence. With this in mind, the overall score will highly award a no losses victory but seemingly dropping below 50 tickets will be enough to negate the 2.5x decisive victory bonus. This isn't liable to scale either I think, if you end a sector with x<50 tickets (say 25) then it'll be lauded as a weak attack.
In terms of teamplay or efficiency I don't think it makes any impact, a team which heavily cooperates, revives, resupplies and repairs one another will be given the same attack rating as a team which may just blindly charge into objectives to click on people assuming they both end up with the same amount of tickets / battalions. Which is a shame since it doesn't really promote cooperation with your team outside of rushing objectives to shoot people.
