Was gonna make a long ass post but i'll just condense it and keep it brief.
Her normals are lacking, they don't control space well. Her best tool for controlling space is F4 which is somewhat slow (not terrible by any means) and leads into a safe blockstring. Only issue is that it has a lot of pushback on both hit and block. So it's not like you can check them up, then go into pressure. At best you're going to be checking them up on block and resetting the neutral game, or if it hits you've done your ~12% and they're at full screen. Compare this to other characters like Cage or any of the other top tiers minus Kitana, who not only space and check you up, but on block can continue pressuring due to the range they're left at.
Her projectiles are crappy for spacing purposes, the first one does 1% so her cancelling daggers literally tickle you. I'd go as far as to say its better to eat the first dagger than to block it, because they deal so little damage and because they build her so much meter on block (8 on block to build a little over a bar iirc). And lord knows you don't want Skarlet to have meter.
Onto her strong points:
Slide is great, it's -3 on block and has the whole empty dash / slide / overhead slash mix up to it. Her pressure, if she has meter and gets you standing is some of the best in the game for sure. She has a great comeback factor with her ridiculous frame advantage and potential mix ups. She has average pokes overall, nothing superb except maybe D3 (small hurtbox) and nothing overly crappy either.
She's number 11-15 imo. About the same tier as people like Kang and Reptile. Definitely not the "kabal killer" she was said to be, let alone within the top 5.