Jersey is posted as the jersey Seaver wore in his last attempted comeback against Tidewater in 1987.

https://www.ebay.com/itm/Tom-Seaver-...38f4%7Ciid%3A1

Compared to this available picture of that game, the font of the 4 does not appear to be a match, but I cannot exclude an issue of the angle of the action shot.
Thoughts?

https://i0.wp.com/www.metspolice.com...2021.jpg?ssl=1