Size does have a lot to do with the modern game but you can't compromise that for athleticism otherwise you will have lumbering giants that will dominate in a scrum or maul but will lose out getting around the pitch. You have to have powerful but fast athletic players.
There is a distinct difference in backs (which are your speed machines) and your forwards (which are the powerhouses) there are exceptions to the rule like George north and Jonah lomu who are big powerful but fast men.
The game you watched would have been boring because of the type of game the manager wants them to p