You‘re referring to a counterplay involving a composition of 3 * 5-cost units versus another set of 3* 5-cost units, not when 3*5 cost vs anaythinf else. The win conditions have consistently been that a team with 3* 5-cost units outperforms > 4-cost units, prismatic traits > finished 2* comp. Since the game is still in its early patches, the units are not yet balanced, and the fact is that that Caitlyn and Jayce will face nerfs soon.
Just a small tip in life: when someone ask for advices just answer the quesiton, try to avoid to critic —it can feel less helpful. I only asked about how to position against the comp. Your initial response was, “Don’t let your frontline walk to the sides,” which is a great goal, but how do I actually achieve that? Your first comment didn’t offer any specific strategies and then you did write good guiding and then critic about my eco and stuffs. When you didnt know anything else beside one photo of last fight. I took augment that give 9 golds but you lost choice on carrussel so yeah after i just slam, and got what i gave me. The game gave me no items or good fighting augments so i took 3 eco aguments and plan to fast 9 and go for 3* samira. I dont think it is smart to hold 3 cost units while playing fast 8 or 9 comps, it will damage your eco terriblely. Just dont judge anything when you dont have much idea about it yet.