By putting so much merit in the teacher evaluations, the University is assuming that students are mature enough to separate those two factors. Many of us have had professors that we did not like personally for one reason or another, but their classes were very educational. On the other hand, we have also had classes that we have gotten very little information from, yet the professor made the class interesting. When filling out teacher evaluations, students must honestly think about what they have gotten out of a particular class. If you leave a class knowing more than when you came in, if a class causes you to think differently about something or if a class sparks an interest in a field you previously had no interest in, chances are you had a good professor.
Students often complain about boring classes.
What they must remember is that every class cannot appeal to every student. For example, some English majors are not going to be very interested in their math class that they are only taking to fulfill their general education requirements. That does not mean that they will not learn anything. Classes are supposed to educate. If they are interesting as well, that's great.