You have 4 spot, and those 4 spots goes to teams that are fairly good/can make some noise. 90% of the other teams would be in pot 5 and 6 in UEFA.
What would happen if we put USA in Swedens place in our group in this wc qualifier? You'd be competing with France and Holland for 1 spot. Enjoy.
I don't think anyone is saying teams that struggle in UEFA would dominate CONCACAF, however, some teams that are close to qualifying but fall short in UEFA would have a better shot at making it through in CONCACAF.
If you took the 2nd place teams from UEFA groups for 2014 and added the top 4 from CONCACAF to it:
Greece
France
Portugal
Ukraine
Sweden
Iceland
Romania
Croatia
Denmark
United States
Costa Rica
Honduras
Mexico
You wouldn't see all 4 CONCACAF teams go through. (Bad example but yeah...)
This is the way I look at it.
Teams much better than the USA: Germany, Spain, France
Teams better than the USA but its close and USA could beat them out over the course of qualifying: Belgium, Netherlands, Italy, England, Portugal
After those 8, I think there's a drop off to the next level where you have maybe about 20 teams (teams like Wales, Croatia, Serbia, Slovakia, Austria, Switzerland, Czech Republic, Iceland, Denmark, Bosnia, Ukraine, Scotland, Ireland, Poland, Sweden, Norway, Greece, Turkey).
No question we aren't part of that top 8. I'm not saying we are, we probably wouldn't regularly qualify as a first place team since we are likely to get one of those top teams in our group, but for the second spot, we should be one of the best pot 2 teams, which usually would mean qualification. There's a chance we wouldn't qualify if we got a really good pot 3 team, but there's just as much of a chance we would get a team like Portugal or England as the pot 1 team, and beat them out for first place.
Maybe like 75% of the time we'd qualify, 75% of the time Mexico would qualify. 50% of the time Costa Rica would qualify. After that, maybe Honduras, Panama, T&T, Jamaica, Canada get one participant among those countries per World Cup if we were to say each country has close to a 20% chance of qualifying.
If you dropped these CONCACAF countries into UEFA and combined the spots available, I think you'd find most of the time you get 3-4 teams from North America qualifying for the World Cup.
As for Sweden, I'd think if you guys were in CONCACAF, you'd regularly compete with Costa Rica for third best in the region. I don't think USA or Mexico are much better than Sweden, nor do I think either country are much better than Costa Rica, but I think Sweden would probably only be 3rd or 4th best. That doesn't guarantee qualification either. Costa Rica missed the World Cup in 2010, and Sweden might miss 1 out of every 4 world cups out of CONCACAF. Mexico almost missed the World Cup in 2014. They were a few minutes from being completely out, but we bailed them out with a result against Panama, and they got in from the playoff against New Zealand.