It was said he was so incredibly smart, and lots of people never understood why others didn't like him enough to put him over the top.
I'm guessing there may be some similarities.
Ted IS a good debater, if you score things from the Hahvahd viewpoint, or debate judges. I just don't think most people want an egghead debate champion as president. They watch these things to get a full measure of the person's leadership style or capacity.
In the case of Adlai Stevenson, II, the intelligence image was just that, an image. It was later found that Eisenhower read far more books in a year than Stevenson.