Uh... "Likes to run" only means that that IV is highest.
Note that having a certain characteristic does not necessarily imply that the highest possible value for an IV is present. A Pokémon with an "Alert to sounds" characteristic could have a 6 in Speed (and thus very low IVs across all of its stats since none could be higher than 6) instead of a 31 in Speed.
From Bulbapedia.
So that means, Shuckle could still be slow, just the rest of its stats would be worse.
See http://bulbapedia.bulbagarden.net/wiki/Characteristic