Races tend to tighten up as the election draws closer. So, the generic polls will likely get closer prior to the mid terms. The Dems had an 11.5% generic lead in 2006 when they recaptured the house. George W Bush had a 35% approval rating. It netted them 30 seats. These polls tend to underestimate the GOP vote. Forget about 2016 for a minute.
2006 - Dem 11.5% generic lead = 30 seats.
2010 - Rep 9.5% generic lead = 64 seats.
GOP gains more than twice the number of house seats with a lower generic lead.
The GOP is holding the House easily this time around.
Yeah, we all remember President Romney talking about that.

The stats mean nothing. However, check the Party Excitement numbers, Mike, if you want a fairly accurate guestimate. In 2010, the GOP was 67% to the Dems 49%. It is the exact opposite this time.