In the House I agree with your assessment but not the Senate. No way should it have been lost.
If you look @ Texas, we sent all of our Republican Representatives back to DC (save the FUBAR in Delay's old seat) as well as Senator Hutchinson. All the R's won by wide margins including the Senator. If there had been a giant anti-GOP wave, it would have shown up here too.
The Senate seats we lost were in states that either lean Rat or were roughly 50-50. It doesn't take much in a 50-50 state to send a candidate down the drain.