I agree with Asheesh that the quality of university teaching by tenured professors would improve if the tenure process took teaching into greater consideration relative to research output. And based on my own college experience (reaching back to a good four months ago), I think the unstated faith that the folks who produce the best research will also produce the best teaching is a faith which dare not speak its name for good reason.
But considering which professors get tenure tells you a decreasing amount about the quality of undergraduate teaching, because less and less of it is done by tenured professors. The trend over the past years has been a shift of teaching hours away from tenured faculty and ladder faculty (those with a shot at tenure) and instead onto various forms of transient teachers: non-ladder faculty, adjuncts, post-docs, and graduate student teachers. The academy is being Wal-Mart-ized – labor is being shifted towards workers with less job security, more precarity, and less institutional support.
This trend poses three kinds of challenges to undergraduates concerned with the quality of their classroom education: First, to protect the presence of enough long-term secure faculty to provide effective mentorship and continuity. Second, to ensure sufficient economic and institutional support for transient teachers to allow them to provide the best teaching they can under the circumstances. And third, to foster progress, rather than backsliding, in the diversification of the academy even in the face of casualization and the coercive economic pressures it intensifies.
That’s part of why undergraduates have so much at stake in struggles like this one.