>Basically you have a higher chance to get one if you're a big enough name in the community.
There's actually a reason for this! It just comes down to marketing.
See, making mods isn't too far from developing games, in that half of the work is making it and then the other half is marketing it afterwards. Not just making it, but also convincing people to play it. Whether they like it or hate it, it doesn't really matter, what matters is that they downloaded and played it.
When Joe Doomer releases a mod, there's a risk attached to it. You know nothing about this guy, and you have a limited amount of time in the day. Why should you play Joe Doomer's mod? He can talk about how it's 32 speedmapped limit-removing levels, but you know nothing about his previous work. It might be shit.
On the same day, however, there's been a release by Xaser! Now Xaser, there's a big guy for all of us. He's got a questionable release schedule but nearly everything he puts out is wonderful. And because you have a limited amount of time in the day, you pick up Xaser's release over Joe Doomer's.
Now, that's just one spectator. But it's a likely scenario for a massive group as well. Even if you get roughly a hundred people from the community, a lot of people would be interested in trying something by Xaser over Joe Doomer. And because of this, Xaser's map gets played more, enjoyed more, and is more likely to become an awardee.
Joe Doomer, on the other hand, has to try harder with marketing and work to convince people that his wad is good.