Hmm, it's hard to agree with this. I think you're equating success in world tournaments with professional level of play, which may not be the case.
As a case in point, consider the recent FIBA World Campionship: Turkey played the final with US and gave it a run for its money (at least at the start of the game). Serbia was awesome, too. The US Team didn't even make it to the final in the previous three times (http://en.wikipedia.org/wiki/FIBA_World_Championship#Results). Now, that doesn't mean that the level of basketball in these countries is better or on par with the one in US. It just means that the very good pro players see this as a waste of time and money (and chance to be injured) and don't go. I bet a similar reason applies in the case of baseball.
US has the best players at every position in basketball, hands down. Not quite the same in baseball but you could produce a dominant American team. But might not have the best team always. I think there has been a decline in US baseball and basketball as team sports.
I am not sure I could empirically prove it though. I find it hard to sit through an actual game in any major US sport, though I find myself still following the NYC teams I grew up with (Mets, Giants, Knicks).
In basketball, also, the level of play has come much closer to the U.S. level. The U.S. did not win the FIBA tournament since 1994. They lost in 2006 with LeBron James, Dwayne Wade, and Carmelo Anthony. It's also important to note that several of the best non-U.S. pros sat out this tournament, also. Notably, Pau Gasol, the second best player on the champion Lakers and probably the best big man in the world right now.
The U.S. had to rethink the way they ran their national program after getting embarrassed, getting more continuity with players committing to multiple years. Wade, James, and Anthony came back after losing in 2006 to put on a dominating performance during the 2008 Olympics. I was extremely impressed with how this current team was put together, because I thought they would have trouble handling the much taller teams they would face. Instead, the U.S. smaller but quicker and more athletic players created trouble for the taller teams they faced by stealing the ball and getting out for dunks and layups. Also, Kevin Durant is a beast.
In short, I actually believe that the quality of U.S. basketball got better as a response to the improvement in the international game and the realization that it was not a glorified exhibition. That's quite the sea change from what the original Dream Team faced in 1992.
Just clicking around, Venezuela and the Dominican Republic are loaded with many of the most famous MLB names. The U.S. is, too, but most of the biggest U.S. baseball names I'm familiar with are on there, and they lost any way. Japan has several major leaguers and of course they have the second best professional league in the world (I don't think there's much dispute about that).
So I think with basketball we have re-asserted ourselves as the dominant world power, but only with a renewed dedication and commitment to get back to that place. I still stand behind my argument that the quality of baseball player development is now better in some other countries than the U.S. This is very much like the English Premier League, considered the best league in the world, and with many English stars, but not enough to make England a dominant football power.
And yes, maybe I think about this stuff just a little too much. :)
Do you really watch a lot of baseball? The American roster there looks pretty crappy. They have Jeter (thank god) and a couple other big names but where's the power? Where's ARod? Pettite? Halladay? Teixera? Cliff Lee (god I hate him for how awesome he was in the 09 WS)? Sabathia? Buerhle?
I think the entire setup is bullshit though. You get a bunch of guys who don't really want to be there to play in an "all-star" team that, for some reason, is assumed to have any unit cohesion at all. You're better off just playing championship series in every country and then playing the winning teams, regardless of nationality. I think "The Yankees" is a better team than any "All-Star" bullshit they come up with.
Hmm. I guess it's clear, then, that I watch a lot more basketball than baseball. I do remember, though, this weird thing with ARod not being able to decide which team to play for.
I'm a sucker for international tournaments. I guess I just like the idea of professional athletes organized around something other than who is offering the highest salaries at the moment. I think the U.S. is just starting to come around on the concept.
As a case in point, consider the recent FIBA World Campionship: Turkey played the final with US and gave it a run for its money (at least at the start of the game). Serbia was awesome, too. The US Team didn't even make it to the final in the previous three times (http://en.wikipedia.org/wiki/FIBA_World_Championship#Results). Now, that doesn't mean that the level of basketball in these countries is better or on par with the one in US. It just means that the very good pro players see this as a waste of time and money (and chance to be injured) and don't go. I bet a similar reason applies in the case of baseball.