Here's a real life example of how choosing candidates at a convention instead of through primaries hurts GOTV efforts.
Next Tuesday, Fairfax County, Virginia will hold a special election to replace new Rep. Gerry Connolly as chairman of the Fairfax County Board of Supervisors. The Republican candidate is Pat Herrity.
I'll be out of town, so I requested an absentee ballot, which came in the mail yesterday. That same day, I got a hand addressed piece of AB Chase mail from the Fairfax County Democrats, along with one anti-Herrity mailer from the DPV and mail from a third party candidate running on a platform of low taxes.

What's wrong with this picture? Two mail pieces from Democrats, one a hand-addressed AB chase piece. One from an independent low-tax candidate, who for all I know, could be a Republican (we don't have party listed on our ballots for county offices -- causing confusion if you don't have a sample ballot from your county committee).
Why do I get more Democratic mail than Republican mail? On a couple of occasions, I have availed myself of the opportunity to help select the Democratic nominee when we had no contested primary. But I have also voted in Republican primaries, including the extremely low-turnout VA-8 primary last year.
The bottom line: There is no reason that as a past primary voter who is a supervoter in both primaries and generals should not be getting Republican mail. I also got very little GOTV mail from Republicans in the general election last year -- though I did get robocalls from John McCain in the primary.
A big part of the problem: here in Virginia we select many of our nominees by conventions, instead of primaries, lowering our potential GOTV universe -- especially in critical situations like a special general election in the middle of February when a good turnout operation could flip the executive office in a Democratic-leaning county.
