I am sure our Ernie writes his letters just to create controversy.
I know Ernie was a bit of a cricketer in his young days and half decent half back at rugby too.
No doubt thousands will write in to let Ernie know the exercise of polishing the ball on one side only is all about aerodynamics. Polishing the ball on one side will make that side of the ball try to travel faster through the air because of its smoothness and so create swing and lift.
The run up has a physiological effect on some batsmen too. Watching a rather large scowling man running at you to gain maximum pace so the ball will bounce and take your head off is a terrifying sight experienced by many novice batsmen.
Sir Richard did prove of course that a bowler can be just and at times more effective with a shorter run up so Ernie gets a bit of support on that comment. However not all fast/medium bowlers are as tall and rangy as Sir Richard so those shorter chaps like Danny Morrison need a longer run up to gather pace.

Alastair Bourne, Bethlehem.