I think the Black ops and waw were treyarchs attempt at call of duty 4 with the tweaks the majority of people were asking for to make it more "noob" friendly, without lacking depth for newcomers and less competitive gamers. So, for people who play a lot, and are a little more competitive, the games are lacking, and possibly unbalanced.
Cod5, to me it seems, was basically treyarchs take on cod4 put into WW2 theme. The guns perform the same as their mw counterparts, but their focus on certain details left the game lacking in others, such as map layout (big time), balance in weapons and their use, spawns (goes under map layout i guess), and diversity in weapons while still maintaining a balanced gameplay. I find this to be the case in Black ops as well. While there are a lot of weapons, there is an extreme lack of diversity in the weapon department with a large amount of diversity and attention given to things like kill streaks, perks, and other small things. It is a game for people who want to play it every once in a while at their friends house, and constantly be unlocking new shit that they will already be able to use perfectly well right off the bat. So that's what makes it a better console game imo.
BF3 i hope will be different.