cardinalnation is correct in that OF positioning is for Basic and advanced games. That table inside the front cover may seem a bit overwhelming when just starting out. The reason the table was placed inside the front cover was that it was only place it could appear in the manual and be printed in color.
Anytime one of the unique OF positions are used, a separate die roll is required only for specific outcomes on odd BODR die results. For example, when playing with 5 infielders and 2 outfielders, a BODR outcome of 1B would need an Outfield Position Roll if the BODR die result was odd. This new roll determines if the 1B stands or is changed to a ground out to the 5th infielder instead. It can also turn into a 2B if the single goes to the vacated outfield.
Playing with a 5th infielder would rarely be used. Its an act of desperation when the runner on 3rd represents the winning run in say the 9th inning. Outfield positioning really does not have an impact on overall stats. It can however impact a single game heavily. It adds some of the cat and mouse aspects to the game.
I wouldn't recommend using OF positioning until a player has several dozen games under their belt.