I would imagine better that an arrow pointing forward would set the keeper with the instruction to come out,off his line to close the attacker's zonal space,conversely,the arrow to point the other direction would instruct the keeper to stay closer to his goal line...
Know which directions a keeper is instructed to follow,before the game squad selection is final,by moving the goalie to an outfield position briefly,to select his directive,and move him then back to the goalkeeper's position,if that would be how you would best desire to position the goalie...

Some keepers are trained against one V one,some not...

Defenders cannot deal with every possible avenue to utter defeat...