I'd argue Ian is quite above the average, all things considered -- he's good looking, in very good shape, potentially both intelligent and charming, not a creep, an artist *and* evidently competent in the sack as well. He's mostly held back by his insecurity caused by the experience with Gillian, but it's not really at all weird women would be attracted to him. Actual average guys can't claim half of the strong points Ian has going for him.
No, fatpussy got it right in the regard that Ian is the typical plain average guy that get but magically happens to potenially fuck 7 girls within weeks, something that isn't possible unless you are a model and sex freak with a body count in the four digits or other unconventional circumcstances. It's an improvement over the typical anime story in which MC is a loser who gets mocked, pitied and is hated by 5 girls, but somehow he can score with every one of them if not all of them at once. Still the same basis, since the foundation is a pornographic game with lot's of choices.
He's not above average but plainly not below average that merely fullfills the basics. Good looking? He is just not ugly. Good shape? He can get beaten up reguraly and can only gets muscles in chapter 10, he just istn't overweight like Perry and Stan are.
He isn't a creep, wow, what an acomplishment. He's good in the bed? He can't even get it up.
Holly? Offices usually have fairly boring dry guys since those tend to be who manage to be content in these workplaces, Ian rebelling against Minerva is the outstanding feature that catches her interest since she is overexited of it and regards it as cool and noble when its a double edged sword, since it can also lead him to lose his job.
Alison? Her other choices are Perry and Jeremy. While Jeremy is good if you just want a to droll over, Ian is at least emotional respondent and can listen to her and support here. Again, thats not above average but very basic stuff.
Gillian is inferior to Lena since she is no model and has smaller tits. Mike points out how Lena is hotter than her.
In contrast Stan would need to reinvent himself.
We can all agree that Ian is better than Stan. Is that an accomplishment? No.
I think you're misremembering things a bit. None of Ian's friends is surprised by Ian being able to court Lena -- both Jeremy and Perry are supportive early on, and then all Ian's friend congratulate him on having such great girlfriend, but no one questions this as some sort of thing that's unthinkable to happen.
Perry and Jeremy are surprised that Ian manages to get her attention. Just because they don't question it further doesn't mean that it isn't untypical and unexpected from Ian.
Just because Perry screws up mentioning Gillian one or twice, doesn't mean he constantly has to point out the obvious that Lena is much better than Gillian. Consider that the artstyle misleads in making every female there extremely attractive, when actually there is a difference. Ivy, Cindy, Lena and Cherry are outstanding while Alison, Holly and Gillian are plain.