I have long been a football fan, though in recent years buisness has prevailed over watching sport, so I have kind of taken my eye off the ball, but I did notice that this year Scotland finished second in "FIFA World Cup European Qualifying Group F", and yet failed to automatically qualify for the World Cup finals, instead entering a play-off phase. However, this is different from previous years when Scotland have finished second in the group qualifiers and been rewarded with automatic qualification for the World Cup finals. I also notice the same is true of the European Championships.
I have conducted a quick search of Google to try and find the answer, but the answer is not immediately obvious, so my question is, since when did second place in the World Cup group qualifiers stop being good enough to qualify automatically for the World Cup finals?