Here's the problem.
Hardcore fans don't even know who Barker is. Hell, when HBO is promoting the fight with commercials, they show clips of Martinez getting some KO's, then show "Darren Barker" and show him with his hands up for the crowd. That's it, that's all they show of him. Like really, HBO can't show a few clips of the guy knocking some one down at least?
So hardcore fans in general don't know who Darren Barker is, casual fans generally do not know who Sergio Martinez is...what you think is gonna happen? It's gonna bomb.
At least if you put two fighters that hardcore fans both know, it would get decent revenue. For example Martinez vs Williams, or Pavlik vs Martinez. Let's face it, Pavlik ain't got no causal fanbase either. And even better, if you put a big boxing star in with a fighter who hardcore fans know, then that too would do good numbers. Barker/Pirog/Dzinzuruk vs Martinez are all calling to bomb. Martinez will never make a name fighting those type of guys, and people are crying to see him against Pirog, when he either has a good fanbase. So what if he chose Barker, there's no difference. Both European hype jobs. For me, personally, he already beat the best European fighter he could beat from 154-160 and that's Dzinzuruk. Pirog is trash, Barker is trash, Sturm couldn't even get passed Macklin in Germany without controversy. Dzinzuruk is the best European fighter there, he's the toughest and he got dominated by Martinez. Knocked down 5 times before getting stopped.