One main different between a Brawl battle and Ranked battle is the use of the gladius cards.
In a Ranked battle we see the importance of the zero or one mana cards as they mean additional opportunity for your team. They could be used as your bait for any opportunity attacks as they would usually have the lowest health. Or you could also put them at the front to pick up the first front attack or to the back as a cover for sneak attacks.
But it is different for Brawl battles where Gladius cards are available and most probably will be used by players. Since all Gladius cards have the bloodlust it is very tricky to use low mana or low life cards with the idea of them giving your team additional opportunity BECAUSE IT MAY BITE YOU BACK! Instead of you getting an advantage by using this small cards it may actually trigger the bloodlust that could cost you the battle.
Here's an example of my brawl battle that shows the wrong use of the chicken
https://splinterlands.com?p=battle&id=sm_i5opYQaFVIgK2LufGOXs&ref=rac19
I was so disappointed with this lost as I had to rent, last minute, the epic Earth summoner Xander Foxwood just for me to be able to use Quora Towershed
But to my mistake, I have used the chicken which gave their Gorth the kill thus triggering his bloodlust giving him additional life much more additional hit power
So even with the heal and 2 attack hits of my Qoura I still lost the battle just because the bloodlust was triggered
Poor me for using the chicken. I have learned my lesson and would think more before using those zero cards for brawl battles. :(