It depends on how you look at things.
When it comes to wide receivers, I generally look at yards and touchdowns. Receptions have their place, but I believe yards and TD's are far more important.
I also tend to look at how WR's stack up against their peers on a season by season basis rather than how they stack up against WR's from a different era because the game changes so much.
From my perspective, Monk shouldn't sniff the HOF because he rarely was in the top 10 in receiving yards in a season and rarely in the top 10 in TD's as well.
However, the HOF doesn't really have any rhyme or reason to their voting. So while I don't believe Monk belongs, I can see a supporter's point when they look at guys like Charlie Joiner and Lynn Swann are in the HOF and they weren't all that great statistically.
Irvin on the other hand should definitely be in. He played in on a run oriented team in an era where passing records with the run and shoot and West Coast offenses were going through the roof. Despite that, his stats stack up very well on a year by year basis against his peers.
Rich............