D&D 5e Combat – Flanking?

So the new Dungeons & Dragons 5th edition has minimized the combat system and veered away from advanced tactical rules and Flanking can not be found in the player’s handbook.   I don’t think placing miniatures on a map exactly is really necessary, and sometimes I don’t mind placing miniatures on the table to get a general feel of combat. So being true to the new D&D5e rules, you would need to use a ruler for movement with your miniatures. With the current size of miniatures, then 1″ would be scaled for 5 feet. Gary Gygax would be proud, because those same type rules can be found in my Advanced Dungeons & Dragons