Ok i am going to explain why Frame delay Killed the mameluke unit.
First of all you need to understand what frame delay is, it is a delay while attacking after moving, which means that after moving lets say the ranged unit it doesn’t shoot immediately it has to wait for the frame delay to fire, so frame delay was added to the game to somehow counterpart the hit and runand fast mobile ranged units.
Mameluke was an amazing unit, maybe OP same like SO, but such power is justified for such high cost and how hard is to mass them in realistic RTS scenarios. Adding frame delay to the unit really nerfed the unit so bad, because it does not only nerf hit and run but even moving forward to attack again, as mameluke has 3 range, no ballistics you can imagine how hard it got for that unit to attack and to do hit and run, the unit can’t attack properly cause of the low range it has to move over and over forward or backwards frame delay kicks in delaying their attacks, as result they get more damage than they do.
If this is not clear at this point i will give another example, lets give the same frame delay to PALADINS, ofc if you fight other paladins or champions or basically not moving units you wont find frame delay so bad, but then what happens if it has to engage moving units, lets say foot archers, paladin will hit one time when getting close then when the archer moves back and the paladin moves forward to hit again the frame delay will kick in making the paladin to take more time hitting, depending on how much the FD is the paladin might even not to hit the archer if its keeps moving backwards, while the archer keeps firing and making damage the paladin with no range would struggle and lose battles that they shouldn’t. The same happens to the mameluke after the change.
Why was FD added to mameluke? well back at the HD the mameluke was a very oppressive unit for CBA and very low level games so the devs were getting tons of complains, then they were about to release new units to the game that all of them would get destroyed by this old unit and no the devs have been clear they want to release new OP units and civs for players to test them, so it was the perfect excuse to kill the mameluke, the frame delay after several years haven’t been removed.
So the next time you might be wondering how to make the unit strong again, i hope you understand how the frame delay is a mechanic that doesn’t belong to the mameluke or basically melee units, it literally destroyed the unit, reducing its cost or boosting in any other way is not going to change anything, you will be creating a different unit than the original that was well designed.