Can't you say the same about US players though? I mean, yeah, there are more successful American players, of course, but there are also a lot more American players in the discussion, so I don't know if you're really talking about a success rate, as much as you're talking about a success raw total.
I think things should be taken on a case by case basis, not all international players are the same, or are developed in the same way, and the same goes for American players.
BTW, Faried is definitely a better athlete than Biyombo.
I did the research a couple of years ago, and the percentages favored the US players by a considerable amount. I spent the last few hours looking for it and couldn't find it, so at the moment I have nothing to back up my claim. Sorry, my bad! One does have to remember that they do play a different game to a degree. The bigs can live in the paint. Their blocked shot, or goaltending rules are different than ours. Whereas in the US we operate more on a star system, and they don't. So its easier for US college players to fit into the NBA, than it is for international players. So the failure rate being higher shouldn't be a surprise. When you add in that their a lot farther from home, and in many cases language, the adjustment becomes harder. Our customs are different, and our food is different.
So, in many cases its not so much about overall ability, as it is adjustment, and commitment to that adjustment. Right now, this minute, as much as Casspi wants to be a star in the NBA, there's probably a large part of him that wants to be back in his homeland. Thats where he's comfortable. And thats what he has to overcome if he wants to succeed here. Thats not unique to him. None of this is true for US players. Or at least not that extent. You may not be able to find good grits here in california, but the language is still english, and the customs are still familar enough. I just think its a lot harder for international players, and only those that are very talented, and have the commitment succeed.
By the way, I also believe that Faried is a better athlete than Biyombo. Certainly not a knock on Biyombo. There's nothing wrong with his athleticism. As you know, I'm more of a skills guy anyway. Too many great athlete's end up relying on that athleticism far too much, and never develop the necessary skills. I'm not sure how many people notice, but a lot of less athletic players, that are very skilled, end up having longer careers than players that rely mostly on athleticism. Look at Dwight Howard. He's just one knee injury from ending his career. I don't wish that on him of course. But he hasn't really developed his skill set much beyond what he had when he came into the league. He's gained experience of course, which has helped. But his game relies greatly on his athleticism. Take some of the athleticism away, and how good will he be?
A player like Pau Gasol however, who is an average athlete, but a very skilled player, could lose some of his mobility, and still be a good player because of that high skill level. And because he doesn't rely on playing above the rim, there's less chance of him suffering a severe injury. Of course Larry Bird didn't play abover the rim, and still suffered a back injury. So you never know. He did manage to play with that back injury for a few years though. I doubt he could have done that if he was a high flyer.