Perhaps assuming you are talking strictly about the AP Award.
Dan Fouts never won the award as well even though he lead the league in passing yards from 1979 - 1982.
Len Dawson never won the award even though he had the highest completion % from 1964 to 1969
Eric Dickerson held the rushing title for 4 seasons including 2105 yards in 1984 yet he never won the award.
Merlin Olsen was one of the most consistently dominant players to ever play in the NFL and he never won the AP award.
IMO the AP award (which isnt the only player of the Year Award) really doesnt mean all that much. Drew Brees won the Bert Bell Award in 2009 which IMO holds more weight.