I thought she was the right person for the position, yet it turned put that she was quite useless.
A. Because I was expecting her to be competent, I was shocked to see her perform rather badly.
B. I was mistaken about her suitability for the position since she proved rather incompetent.
C. Contrary to my initial impression, she was not totally unsuitable for the position.
D. I was right in thinking that she was totally useless for the job