Kalista Damage WAY Too Strong

I may just be frustrated and underestimating Kalista's damage, but last time I played, which was in patch 5.14, her damage was balanced and it showed correctly. Now I've played in the 5.15 patch, and now in the beginning of the game, when the Kalista had 73 AD, and could 3 AA me and then rend, instantly killing me. It happened all game. Again, I can't fully prove it's a bug, but based off of stats, prior game play, and balancing, this seems a little too much power for her. She killed me as Thresh, Vayne, and Riven in like 8 seconds in the BEGINNING, of the game! Thanks for reading!