I think you're missing the point -- they aren't even advertised as the "best the sport has to offer" -- these are guys who have gone unnoticed and have not been given the opportunity to be in the big show and the elimination process combined with the boot-camp style (at least for Tito's team) training regimen gives them that opportunity to join the elite that make it into the Pay-per-view. But in some cases, these guys are the real deal (e.g. Diego Sanchez, Forrest Griffin, Bonnar, Bisping...)
It's like watching a minor league baseball game -- there are a few potential stars there but some guys are just below average.
Regardless, the formula clearly works, the audience clearly loves it and the show has taken the entire sport and the UFC to a whole new level in terms of business success and marketing.