I presume you also wouldn't go near a player in, say, Eredivise or Jupiler League? Ruling out every player from particular leagues doesn't sound like a great transfer policy.
MLS isn't as good as the Premier League. Obviously. But it has some good players, like Besler, who are up to the Premier League's standard. He was certainly up to the standard against Ghana, Portugal, Germany, and Belgium.
Yes, Lukaku did skin Besler in the knockout match. Or to be more accurate: After Besler had played more than 90 minutes, Lukaku came off the bench in stoppage time--fresh --and got the better of Besler. Imagine that.
He's a good player and would make us a better team.