Slack in universities?

Earlier this week my friend was complaining to me about a class which is about the topic she likes a lot, but she said the professor always seems to come a bit unprepared, and the lectures are a little disorganized. I am not making the argument that the professor is shirking but the word slack we learned in class quickly came to mind. Unsuprsingly, Tenured faculty has a much lower termination rate when targeted for sanctions than fixed-term faculties(16 percent v. 53 percent). It's also universally agreed that it's quite hard to get fired as a tenured professor. So I thought, in the rare case when a tenured professor really is shirking, can we avoid it? I thought about it, and the conclusion I reached was no.

In class, we talked about how to avoid employees from shirking. 1. monitor(have the knowledge of whats going on). 2. well-defined objectives)single dimension output) 3. frequent performance reviews. 4. secure many alternatives. Based on this metric, it seems to me that it's quite hard to avoid tenured professors from shirking, for the reason that 1. Monitor: It is often difficult to monitor the daily activities of tenured professors since there are various forms of academic work (teaching, research, etc) and can be private. 2. 2. well-defined objectives: Unlike many roles, teaching and research outputs are difficult to quantify consistently, and success in these domains is often subjective. 3. frequent reviews: Tenured professors have limited performance reviews compared to non-tenured faculty. 4. Alternatives: Yes, there may be some alternatives, but universities have limited options to replace tenured professors, given that tenure is a form of job security that makes dismissal challenging unless there is a serious misconduct.