I thought she was the right person for the position, yet it turned out that she was quite useless.
A. I was mistaken about her suitability for the position since she proved rather incompetent.
B. Because I was expecting her to be competent, I was shocked to see her perform rather badly
C. I was right in thinking that she was totally useless for the job.
D. Contrary to my initial impression, she was totally for the position.