Now that may be the problem. Perhaps the mathematics department should be moved to Engineering. Stanford did that with computer science back in the 1980s. It used to be part of Arts and Sciences, run by a rotating committee, and was graduate-only. The education side was disorganized, with schedules and staffing not matching up with admissions. The entire department was transferred to Engineering, was better organized, and got much better on the educational side.

The research side was dominated by logicians to and through the "AI Winter". Then they brought in machine learning people for the DARPA Grand Challenge, and that turned the research side around. Now the machine learning people are in charge, and most of the logicians and expert systems people have retired.

Science progresses one funeral at a time.

While EECS treats its lecturers well, they are still essentially adjuncts. Lecturer SOE is very different from just lecturer, because as you pointed out they have tenure. From what I can tell of my time there, the EECS department very much appreciates good/great Lecturers SOE teaching the lower div classes. Apparently the math departmnet does not.