Was Roy Hobbs an Agent of God?

I think it's quite possible that this film can be read as Roy being a supernatural agent sent to protect Pop and save the Knights.

I think he died after being shot but was later sent back into world.

He was signed up after suddenly reappearing and being at the Oilers for just two weeks; as the lightening comes in from nowhere, he literally knocks the ball out it's cover on his first hit; Bump Bailey gets removed in strange circumstances, opening up Hobbs' position in the team; he bursts the netting with his first pitch; he then takes the team from nowhere towards the championship; he has no interest in material gain, being incorruptible, and even the Judge's attempt to take him out is thwarted as he gets off his "death bed" to see the Knights home despite being advised he will die.

He was brought back, did his job and then returned to the afterlife - don't forget the blood pouring through his shirt at the end. The final scene - playing catch with his son - takes place once they are reunited in the afterlife. This is shown by the symbolic shot of the ball continuing up past the floodlights into the heavens then descending into his son's hands in the farm.