1.
outfield
The area of a baseball field beyond the infield, or the players who defend that area.
2.
outsiders, bystanders
People who are not directly involved in a situation but make comments or criticism from the sidelines.
外野 literally means "outside field" and refers to the outfield in baseball. It is also used figuratively to mean people who comment on matters they are not directly involved in.
Common collocations
Usage
The figurative sense (meaning 2) often carries a negative nuance, implying that outsiders should not interfere.