So suggests Jeremy Pierce at Parablemania.
From what I've heard and read of the Tea Party, while they obviously have some (very?) conservative leanings, one thing I've heard out of many tea partiers or those sympathetic to them is that they don't want to be "the guys who help the Republican win just because he's a Republican". In fact, there seems to be a heavy feeling of being anti-incumbent, period, rather than just anti-Democrat. It wasn't like Bush or the Republican house and senate did a bang-up job when they were in power - not exactly the era of small government, that. (The SCOTUS appointments were the best things to come out of Bush's presidency, and that involved a near revolt by the Republican base.)
Coming from PA, I recall how many times Republicans were told how important it was to support Arlen Specter, to turn a blind eye towards any problems that anyone may have with his policies or his voting record, on the grounds that he was the Republican incumbent and Republicans support Republicans no matter what. It turned out Specter himself wasn't too keen on that advice, because he bailed on the party the moment that seemed like the best move for his political fortunes. Of course there was also Jim Jeffords and all manner of other incidents.
I suppose what I'm getting at is, even if it were true that Tea Partiers are costing the Republicans seats (On the whole, I doubt it, but you never know), I think the response of many would be "So what?" Should they vote for the candidate they dislike purely to get a Republican in office? Better yet, why regard it as a failure of the Tea Party as opposed to a failure of the Republicans themselves? If a given candidates' actions or political leanings result in the base abandoning him, is it the base's fault or the candidate's fault?