I think you may have a point. It is said in the manga that Shikamaru has an I.Q. of over 200 which is blatantly false. Kishi writes the manga so a character can only be as intelligent as him and it is very unlikely that Kishi has an I.Q. that high so Shikamaru automatically has one which is lower.
Also characters with average intelligence are sometimes nerfed to make smart characters look better. Example of this is when Naruto was dumbfounded when Nagato used CT despite the fact he himself fought Pain and studied those techniques. Itachi had no clue but he still managed to come up with a strategy despite the fact someone with knowledge couldn't. Anyway, while Shikamaru is extremely smart in comparison to other characters in this manga, the smartest character he outsmarted was Temari. Seriously, it doesn't take a genius to outsmart Hidan or Kin. For this reason I think he is overrated because people say he wins a VS battle because they think he'll find a way but look what happened in his fight against Tayuya.