Theres not much that goes into a heroe’s foundation. The only things you have to take into account is the hero’s main ability, their model, and their attack animation.
Drows attack animation is slow so to be a carry she has to deal a large amount of damage. She doesn’t have the attack speed to accomplish a fast kill. What makes it worse is frost arrows slows down her attack animation. For these reasons i have no idea why people play her like a carry.
Now the model. The model of drow ranger is an archer. That mean she attacks from a distance. She can be a good adversary against mellee heroes because of the distance she attacks from..
Lastly the main ability. Its a three way tie between gust, marksmanship and frost arrows.
Frost arrows allows her to be an initiator, support or ganker. As initiator she can surprise enemies and keep them in walking distance when a skirmish begins. As a support she can slow enemies down to keep them in range of attacks. As a ganker she can attack from the shadows and surprise an enemy.
Marks manship gives her more damage and allows her to carry. It is an ability that allows you to gamble your chances of victory because damage is not a choice its randomized/
Gust is also an ability of choice as a main ability. This allows her to gank and initaite and support. While she ganks with this ability she can keep enemies from being retaliating during a fight with this ability. As support she can keep enemies from feeling useful. and disable their ability to retaliate