Amongst every race there are going to be people at the higher end of the intelligence spectrum and some at the lower end. If anyone remembers Trading Places, the crux was you can take a rich, white, well-educated individual and put them in a bad situation and they will deteriorate. Conversely, take a black, poor, low-educated person and put them in a good situation and they will rise. Yes it's a movie but there's certainly some truth to it - put individuals in certain supportive environments and they will succeed.Yet the majority of the engineers I studied with who spent their days focussed solely on school work did not end up getting management level positions and are out-earned by those of us who balanced studying and sports/clubs/etc.
We had the discussion here a while back about IQ and race and the result was the science does not support the claims of significant variation in IQ by race.
p.s In North America, Asians (beyond being an extremely broad group) represent a pretty small number so any stats have to be taken with a grain of salt.
The difference between most Asian families and many standard NA families (ethnicity irrelevant but kids Canadian born or mostly Canadian raised) is the general work ethic. You can see this amongst Jewish families (why are so many Jewish people doctors or successful businessmen?) and EI's - it's a work ethic, not necessarily just innate intelligence. Take any child and ingrain in them a strong work ethic and a desire to succeed and they will do so in their own way.
To your point about focused/well-rounded, it's not hard to understand that there's more to any job than just the technical side. Many people know their own shit but cannot present it to others or socialize well with others. You have to have a combo of both to rise in any organization (knowledge and social skills). A focused person will know all the small details but is not trained or accustomed to thinking strategically or considering the big picture - they are highly focused on their niche only. MBA programs were created for engineers originally to help them understand the business side of an organization.
I think each group has a certain culture that persists and that's why Asians and EI's are considered smart (there are other groups too of course) but the culture revolves around working hard, not socializing, and aiming to make no mistakes. I think there's definitely segments of different groups that have this same attitude but definitely amongst some groups there is a percentage of that group that does not stress hard, honest work will help you to succeed.