World Cup: vs the other 31
When I was looking up the Czech Republic's preformance against the top teams in their group, I got the idea to take a look at how all 32 World Cup teams have fared against only each other. So I went through each team's list of games on FIFA's web site, and recorded the information. This includes every type of game: friendlies, qualifying, continental championships, etc.
There's a lot of things to consider here. First, the number of games and quality of opposition for each team. And looking at the numbers alone can't tell you things like Brazil using their U23 team in the 2003 Gold Cup. But it's still very interesting to look at, and I don't think you'll find this stat anywhere else.
vs other World Cup teams
(ranked by PPG)
First of all, Iran is at #6. They did beat Ukraine in Kiev, but it's not like they have an incredible W/L record, or GD. So I wouldn't put much stock into it.
One thing I think we can take from this is that the lesser European teams haven't done so well. This despite every European team except Serbia favored to advance from their groups. There are going to be at least 3-4 of them who don't advance. Due to the European system, they really don't have to beat any great teams to qualify. Now of course teams like Ireland and Romania are pretty good, but it's not like any of those teams would fare much better on this list.
Europe's finest though, have nothing to worry about. Spain, France, Italy, and England are all very impressive.
Switzerland is the only team without a win, and they only scored 3 goals in those 8 games. Serbia's only victory came against Tunisia in March. Speaking of Tunisia, the've had more games than the other African teams, with a few decent results. Ranked higher than I would've though.
Two teams with absolutely horrible records are in the same group: Ecuador and Costa Rica. Poland's not too impressive either.
BTW, from 1998-2002, the USA's record against 2002 World Cup teams was 15-12-4. That's 1.58 PPG, almost exactly the same as the past four years.