In California Democrats usually do much better in the general election that they do in the primary. I'm not entirely sure of the reason for this. Their voters are ones that are less likely to show up in primaries, but other states don't have this pronounced a difference. As a result Democrats tend to do far better in the general election than they do in the primaries. In the past this wasn't a really big deal, but with top two it cost them a congressional seat and maybe an assembly seat. Still, it's hard to look at the general elections results and find Democrats have a lot to regret.
This comparison was made by totaling the Republican, Democratic, and third party votes in the primary and general election for all candidates of that party. In 2008 and 2010 Democrats improved by an average of 11% between the primary and the general in congressional seats where they got between 38 and 60%. They averaged a 16% loss in the primary and a 5% loss in the general.
This year I looked at 59 seats in the assembly, senate, and congress that were competitive/semi-competitive. On average Democrats improved by 15.3%, an increase over the past several cycles. This likely happened because Democratic turn-out and thus turn-out overall was lower in the primary, while Republican turn-out was respectable. Democratic turn-out was strong in the general, while Republican turn-out was down slightly.
I listed the seats based on the primary spread and included the general election spread and the difference between the primary and the general. A positive result is a Democratic win and a negative one is a Republican one. One thing that immediately jumps out is that the better the Republicans did in the primary the more the district tended to move toward the Democrats in the general election. The first group of 20 seats moved 10.3%, the second 15.7%, and the third 20.2%.
Thus Democrats were more likely to gain ground in seats where they were outspent than those they outspent Republicans. They gained the most in those districts where they had no shot and didn't even bother trying to win.
Some of this is likely due to both parties having a floor in the general election, but why did Democrats fall so far below that floor in some primary elections and not in others? If Democrats were able to increase turn-out from the primary to the general election is SD-21 enough to close the gap by 23%, why didn't they also increase turn-out in nearby SD-19, 25, and 27?
After losing several elections that looked one sided in the primary Republicans can't get complacent for general elections in 2014. Republicans lost in the general election in every contest where they lost the primary and even those they won by as many as 11.7%. They were 4-5 in primaries they won by 14-19% and were 25-1 in primaries they won by 22% or more. So while Republicans lost a seat where they won the primary by 34%, there is a safe territory.