Rick Perry and Newt Gingrich have failed to qualify for Virginia's Republican presidential primary. Gingrich has responded typically with bombast and inappropriate historical metaphors. But rather than criticizing the campaigns as incompetent or Virginia's rules as bizarre, we might note what this means for our understanding of party nominations.
One of the things that party insiders provide for their preferred candidates, in addition to money and endorsements, is expertise. That covers a wide range of things, including people who know how to read polls and put together ads and basically run a campaign on a national scale. But it also includes people who understand the arcane rules of nomination contests in the 50 states. Those rules can get weird. For Virginia, a candidate needs 10,000 valid signatures, including 400 from each of the state's 11 congressional districts. Pennsylvania Democrats vote for delegates, rather than candidates, and Hillary Clinton had some problems there in 2008 when her campaign failed to find a full slate of loyal delegates prior to the primary. Caucuses bring their own level of weirdness that primaries lack. Texas has both a primary and a caucus.
The point is that someone with insider backing within the party doesn't usually make mistakes along these lines. They're provided with people who can avoid these snafus. That doesn't mean that outsider candidates can't achieve this level of expertise -- notably, Ron Paul made the Virginia ballot -- but it's a lot harder when you don't have the backing of party elites. This is one of the ways that party insiders pick winners.
Update: Important point from Josh Putnam: This is the first time that the Virginia GOP has bothered to validate signatures. They now do so as a result of an independent candidacy for the state legislature in 2011. Again, a well-backed presidential campaign would know these details, but this is an important wrinkle.