Had to look it up
Gehrig had multiple 10+ fWAR seasons as a 1B, Jimmie Fox had one
In more more modern times highest have been
Pujols 2003: 9.5
Giambi 2001: 9.2
So yeah it's super rare/almost impossible for a modern day primary 1B
I thought maybe but i had Chat GPT dig into it:
Here’s the Blue Jays’ team run support per start in 2025 (RS/G)
Eric Lauer — 6.53 RS/G.
José Berríos — 5.93 RS/G.
Kevin Gausman — 4.83 RS/G.
Max Scherzer — 4.61 RS/G.
Chris Bassitt — 4.13 RS/G.