As in 2008, there will be Republican pick-ups where they win by a large margin. What about the close ones? In sports they say that the good teams win the close ones. Is it the same here?
In 2008, it wasn't. Not surprisingly, since more Republican seats were in play, more were decided by 10% or less. They pretty much broke evenly.
In 2008, four of the five forecasters made forecasts. Real Clear Politics, which is favoring the GOP most this year, did not. When all of them agreed on their forecast, flipping or not, the party they agreed on won 79 of 80 times. I think we can count on those. The good news for Democrats is that right now they only all agree on 15 Democratic seats that'll flip.
They did fairly well on the seats that actually flipped. The Crystal Ball was the only one that made predictions on all of them. Larry Sabato got 80% of them right.
Because the Crystal Ball predicted every race their winning percentage was lower. They got 75% right. If they're 75% right this year, the GOP will get a net 21 of the seats they have flipping now. The Crystal Ball has indicated they'll move more seats to the Republicans. Considering he still has 31 seats in toss-up, this number will grow.
Three forecasters left seats in the toss-up category in 2008. As they expected these seats broke fairly evenly. If all of the seats Cook predicts to flip do, as they did in 2008, and the toss-ups break evenly, the Republicans will be win a net off 44. Based on Rothenberg, it'd be a net 34. CQ would have a net of 33.