Midterm elections are often 'wave' elections - an election in which one party sweeps nearly all of the competitive races and makes large gains in both houses of Congress. However, 2014 doesn't look like it will be one of those wave elections, despite what the media is saying.
For this year to be a wave for the GOP, both parts of that definition must hold true. First, the GOP would need to win most or all of the 'purple' state races and even pick off some of the more traditionally 'safe' Democratic seats. Further, they would need to do this without taking losses in traditionally 'red' states.
2010 was no doubt a wave election for the GOP (as was 2006 for Democrats). In that year, Republicans won in Wisconsin, Indiana, Ohio, Pennsylvania, New Hampshire, North Carolina, and Florida, and even picked up a seat in deep blue Illinois. Further, they would have also won in Nevada, Colorado, and Delaware had the party not nominated more extreme candidates who couldn't appeal to the independents. Additionally, Republicans didn't lose a single seat held by an incumbent of their party.
That year, the GOP picked up seven Senate seats and a whopping 63 House seats (we'll talk more about that later). This year, the party may pick up an additional seven seats, but this time, it's different.
In 2010, the Senators up for re-election had won their last election in 2004, a moderately good year for Republicans. Therefore, the party didn't have many incumbents to defend in the more Democratic states. However, this year, Democrats are defending seats they won in 2008, a banner year for the party. Now, Democrats have incumbents running for re-election in deep red states such as Alaska, Arkansas, South Dakota, Montana, and West Virginia. It shouldn't be any surprise that even in a neutral year, Democrats would lose most, if not all of those states, and by fairly large margins.
But here's the rub: most of those states (not including Montana and West Virginia) are still highly competitive this year. Sure, the GOP may take all of those states, but it won't be by blowout margins.
Additionally, to qualify as a 'wave', Republicans would need to pick off Democratic-held seats in most, if not all of the 'purple' states, and possibly pick up a more traditionally Democratic seat, such as Minnesota , Michigan, or Oregon. So far, of the purple states, Republicans are ahead in Colorado and Iowa, but behind (slightly) in North Carolina and New Hampshire, and they are being blown out in Virginia.
Michigan was once thought to be a competitive swing state, but the Democrat, Gary Peters, is now way ahead of his Republican rival. Minnesota and Oregon are also not even close.
To further drive the point, Republicans would need to easily hold on to their seats in red states. But that isn't happening either. The Independent candidate (who will probably caucus with Democrats, if he wins) Greg Orman is neck and neck with Pat Roberts in Kentucky; Democrat Michelle Nunn is leading her Georgian rival, and Kentucky's Alison Lundergan Grimes is only a couple points behind Senate Minority Leader Mitch McConnell. These red state races will be close, indicating there's not going to be even a small wave for Republicans this year.
Finally, with respect to the House of Representatives, the GOP is expected to pick up between 5-10 seats, but that isn't especially surprising given that most of those seats are in districts that have been gerrymandered by Republican state legislatures in order to help the GOP candidates.
Could a small wave still form? Yes. It would require Democrats losing in (at least) Colorado, Iowa, North Carolina, and New Hampshire, as well as Republicans winning by larger than expected margins in Georgia, Kansas, Kentucky, and the remainder of the red states. Further, the party would need to pick up close to twenty seats in the House.
Until evidence of that begins to appear, however, let's stop calling this a wave election.