By average I don't mean to bash, just someone who's never been considered a top level fighter. Gives everyone a fight but loses to top competition.
Leben, He always comes to scrap, never looks to cruise into a decision win. Always looking for the KO or sub. Your always in for a good fight when he's in there.
Lytle, Always entertaining, a career's worth of KO's and Submissions.
Tank, had zero technical striking, No subs, some wrestling, But he was packing some fuckin anvils! His persona sealed the deal, Dude literally went from the bar stool, to the cage, back to the bar stool.
Dan miller!! 
Spencer fisher always came to fight, Same with Marcus Davis.
Robbie Lawler
I'd have to go with Nate Diaz, but it would changed on what you consider average
Brad Pickett. I want to qualify that though, because I don't believe he is a truly average fighter. I think he is top, top level, but will never win a title because he is gonna drop some close decisions due to the scoring system.
Catsmasher
Lytle
Scott Smith
Robert Emerson always brings it and is from the area im from.
Not saying Emerson is average, but ranking wise because of activity as of late
Cruz2ninjafoya - Robert Emerson always brings it and is from the area im from.
South County? Hello neighbor
Thiago alves... I might consider him a bit above average.... Can't beat Fitch or Gsp though.
gage949 -Cruz2ninjafoya - Robert Emerson always brings it and is from the area im from.
South County? Hello neighbor
Yessir
I enjoy Evangelista Santos not the best record but always exciting. Not "average" yet fits the bill for this discussion.
Gina Carano
Lets not forget Don Frye, although he was considered a top level fighter in his hayday, he continued to pack the budo well into the later stages of his career.
Evangelista Cyborg
Melvin Manhoef
Krazy Horse
Jens Pulver. Nowadays, Wand, as sad as that is.
Jason macdonald for sure.
Sam Stout, Chris Lytle, Pat Berry