Maybe I just enjoy defending the dead horse that keeps getting kicked or the indefensible (like Monday's Nights call against the Packers), but here goes one last post as the replacement refs exit through the back door
I readily admit that the regular refs were and will be better than the replacements. My basic contention is that it is impossible to tell how much, at least using data that is widely available and discussed. Many of the replacements' critics would use Monday's egregiously bad call or other missed calls as prima facie evidence of the replacements' inferiority. How soon these critics seem to forget the 2011 worst calls that had a major impact on the game including one in the Packers' favor. All 2010 lists include the silly "going to ground" call against Calvin Johnson where the officials tried to hide behind technicality. Here's a list of worst calls ever which includes incredibly funny 1998 coin flip fiasco -- imagine if a replacement ref had pulled that, it would be on an endless C'mon Man loop. The list includes the entire 2006 Super Bowl game where several mistakes piled up against the Seahawks (mabye Monday Night was a bit of karma). Here's the referee lamenting his errors in a 2010 article.
If bad calls don't indict the replacements on their face, then the amount of complaining does. The trouble here is the classic chicken and egg problem. Is the enhanced complaining the result of poorer calls or is the complaining the cause for the view of poorer calls. With meticulous review of game tapes, NFL officiating insiders maybe able to separate these two from each other, but merely relying on media or coaching noise doesn't disentangle them.
With my indefensible defense out there, I'm as happy as anyone else that the regular refs are back on board. Not only will games be officiated better, but everyone can go back to standard complaining about calls. As long as the replacements were in place and a viable (and better by whatever margin) substitute in the wings, perception became reality. With the regular refs, there is not fall back, so coaches, media, and fans, while grousing, don't bang the drums for some alternative. Instead, it's treated as a given.
I will add a defense of my proposition that the main advantage of regular refs is through their build-up of training (however long that takes) versus some underlying rare skills. I would identify 3 main skills that NFL referees need: 1) intelligence to deal with complex situations and tasks, 2) emotional control to deal with stressful situations, and 3) physical traits that allow them to be mobile and observe/process fast moving action. Since all NFL refs are currently male, I'll start with the male population between the ages of 25 and 60. If we take the top 25 percent of the distribution of intelligence, handling stress, and key physical traits, then that culls the 67 million down to about 1 million. (The outcome would be a bit different with dependencies between these traits.) Why a person would need to be a lot farther out in the tails of any of these skills distributions isn't at all clear to me unlike the players where small differences in ability show up as big performance differences. In fact, the top half of the distribution would likely be sufficient.