My apologies  I did not see your comments before making the most recent edit to the article  I have no problem with retaining the big three concept  The sentence in question just needs to be written a little better  We should eliminate the words big three and replace them with something more descriptive and less simplistic  I like your wording three design elementsfirepower protection and mobility Perhaps this could be used to replace big three with some additional wording  How about The three principal design elements   For the record reliability refers to the entire weapon system not just how well the tank gets around the battlefield  For example if the main gun sights dont maintain proper alignment you cant hit anything  Reliability right You can have the best tank in the world in terms of battlefield mobility but if it keeps throwing tracks its unreliable  Anyway a rewrite of the sentence in question will almost certainly solve our problem