"Bad" is a very relative term. Even if the sales of iPhone mini really are only a single digit percentage of all iPhone sold, that would still be in absolute numbers something in the range of 10 milion units - a lot more than other manufacturers sold of a single model.
Of course we're talking about relative to Apple's revenue expectations and level of investment.
The iPhone 12 mini project team won't pat themselves on the back and say, "We sold more than this smartphone manufacturer based in India! Let's go ask Tim Cook for a raise!"
If you're in the Ivy League, you don't compare your grades to someone in community college.