That’s Brendan Nyhan’s “conclusion”:http://www.brendan-nyhan.com/blog/2010/10/did-the-tea-party-weaken-gop-candidate-quality.html:
bq. More importantly, while it’s true that Tea Party candidates are less likely to have previously held elected office in more contested races, the differences are smaller than one might think — 48% of non-TP challengers in competitive districts (25 of 52) versus 33% of TP challengers in competitive districts (18 of 54) and 53% of non-TP open seat candidates (15 of 28) versus 43% of TP open seat candidates (6 of 14).
bq. In short, the Tea Party movement has affiliated itself with a surprising number of non-amateur politicians in competitive and open-seat races. As a result, the GOP still has a candidate quality advantage in the House races that matter most.
There is a tendency for some observers to assume that an ideologically driven movement — especially if it appears to contain some “fringe elements” or whatever — isn’t going to be politically strategic. The emergence of a few high-profile oddball candidates that have the support of the movement — your Christine O’Donnells — only seems to further this perception of movements like the Tea Party as somehow lacking the savvy to get behind good candidates. But clearly that’s not true, especially in a cycle when every other political dynamic — a weak economy, a less-than-popular president — gives qualified Republican candidates an incentive to come forward anyway.