Future Person is somebody who posts the outcome of a particular at-bat or play before most other users watching on delayed broadcasts or GameDay see it.

KMT59 is the most well-known future person, who listens to the MLB radio feed which is delayed and posts a player's name with an exclamation point whenever they do something desirable in an at-bat.

Pretending to be a future person provides the opportunity for occasional trolling.  For example, someone might post that Puig has hit a home run and get everybody else excited when in fact, such an event had not occurred.