For many years, the amount of available chest drops has grown and grown, while the chest mechanics remained mostly unchanged. It is starting to become painful.
The chances to find a green troop in a gold chest are about 1:1000 at this point (1/163 * 0,1625 = 0,000969). Everything above purple troops is a completely hopeless cause. Even event keys are at risk of becoming troublesome due to the drops you would want getting drowned in the masses.
This is getting insane. You can not expect all troop upgrades to happen through orbs or soulforge. Handing out more keys is not a solution, especially for lower rarity troops.
If you are not willing to give us an option to trade our own troops for different ones of the same rarity at a 5:1 ratio, as I suggested a while ago (Troop trading system), at least make each chest drop two or three different troops.
It is your fault, that this game keeps growing. Deal with the consequences and do something about it.
(yes, I know it is pointless to write threads, when they remain unheard by anyone, who would matter.)
[Edit:] If that all sounds too much to ask for, an option to CHOOSE from three different drop pools consisting of identical rarities would help too already.