Where's JFK? Surely the Ivy Leaguers would see him as one of their own. Given the probable age of the professors (similar to mine) when they grew up (post assassination) the nation lionized JFK. At least in New England, it seems like half the schools and public buildings built in the sixties were named after JFK.
Where's LBJ? Surely he must be recognized as probably the most politically astute President, perhaps ever, and certainly one of the most effective in getting his agenda enacted. The Great Society, Civil Rights Acts, the Space Race (Kennedy's idea, LBJ's implementation) and, unfortunately, Vietnam.
My thoughts on Carter- Carter almost certainly should be classified as one of the best and brightest-and what he accomplished in his life is awesome, but he was a totally ineffective President. His penchant to micromanage everything and not delegate authority, coupled with a complete inability to effectively deal with Congress, doomed his presidency.
All in all, I wouldn't place a whole lot of weight on this "study" other than as a conversation piece.