2 umpire mechanics, going out on a fly ball

[Steve M]

Generally, in 2-man, I'll chase with any of these:
1-ball on the line
2-ball to the wall/fence
3-charging fielder - either in out out
4-fielders coming together

Almost always, it's from the A position. From other positions, I may well throw an extra set of eyes on the ball without chasing - in those critical situations.