He's gaining traction simply because people are realizing that he'll be the candidate. That's all. There are TONS of polls out there that show that he would be losing to Cruz overall, and in many states Rubio, if there weren't so many damn candidates. The opposition to Trump is getting split, there are very little supporters of Cruz, Rubio and Kasich that would go for Trump if there were still a candidate other than him to vote for.
I mean I guess we are just going to have to agree to disagree because there really isn't a solid answer at this point. While I get that there are polls that may say that Trump would lose head to head every example of actual voting has proven otherwise. I'm sure there is some effect of the nomination feeling inevitable, but then how do you describe the constant record breaking turnout? One of the effects of a candidate feeling inevitable is apathy, people just stop voting because they feel like it doesn't matter.
I was just looking at some of the first few primaries to compare percentages now and then and it's pretty interesting. South Carolina is a good example because there was still a large field at that point, and because of its proximity to North Carolina. The South Carolina primary ended up being.....
Trump 32.5%
Cruz 22.5%
Rubio 22.3%
Bush 7.8%
Carson 7.6%
Kasich 7.2%
Since then Carson and Bush have both dropped out that's 15% that needs to redistributed throughout the field. North Carolina ended up
Trump 40.5%
Cruz 35.5%
Rubio 7.9%
Kasich 12.5%
So he picked up 8% of that 15%. Of course there are other factors, and i'm sure people thinking he is going to win is getting him some vote, but that's a huge increase. If everyone except Cruz dropped out tomorrow Trump would only need 10 of that new 25% which I think he would ultimately get.