Well America isn't very supportive to football, even calling it “soccer” than football like the rest of the world. But it's growing, so the league itself is trying to grow ties with bigger clubs like a pipeline for scouting. Stan Kroenke I believe is the owner for the Colorado Rapids here in America and currently has the biggest share of Arsenal at little over 26% I believe. So Colorado has the mutual agreement with Arsenal for players. I haven't seen any players sent on loan or bought amongst the two, but it's bound to happen.

Also it's for competitive reasons. America believes talent has grown in soccer so they're brining in these massive clubs to play against in order to see how they fare with top competition. You usually see the European sides win, but sometimes you do get results like the New York/Juventus scoreline. But in my honest opinion, it's from the youth players where talent is made. The MLS strictly prohibits players into the league unless from collegiate play or you are with Generation Adidas, a group devised of American players with the sole purpose of growing talent in America. The problem with players only from collegiate play is that they are already 22 or 23. England has the earliest professional status at the age of 16 as other European clubs in Italy, Spain, etc. settle at 18 so players' bodies are more developed. If you're 22/23 just coming into professional play, I think it's already too late. It's said that most soccer players reach their prime, their best years, at ages 27-31, but I think the good players have the most success at the early years. Everyone's dream when playing is to be the best so why not allow them to have that chance and let them start playing professional earlier like European sides than having them get an unnecessary full education. People who plan on playing soccer for the rest of their lives do not need a degree, just a ball, a pitch, and someone to dribble past by to score.