Its about statistics and probabilities. A team losing at the last few minutes of a game by a manageable margin will foul to get possession back. In non-blowout games, around a third of the free throws taken occur in the last few minutes. Statistically, the more free throw is given to a player - the more chances to miss.
In the example given by the original poster, it may be possible that the stronger FT shooter had to take his free throws in the "last few minutes" scenario - where in real life the pressure/stress is much more particularly for an away team.
also don't forget that the last few minutes of a game, players tend to be the most tired, and tiredness, as pointed out before, can lead to missing free throws.
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