With good leadership, untalented junior engineers can become very productive junior engineers. I've seen it happen. Within weeks some kids fresh out of college, who had been taught everything mainly in Java (this was still the JavaSchool era, more or less) were proficiently and happily contributing to our C++ code base. They were pretty good, but they weren't Carmack or anything.

Now if your leaders are untalented, you have an organizational issue: you're promoting schlubs. Why are you doing that? Stop doing that.