Yeah, Trump basically had a perfect storm of things in his favor here.
The fact that the GOP had over 10 contenders to split the vote for a large portion of the race was a huge factor.
I mean, if you look at Trump's performance in those early days, So the first 32 States up for grabs between February and March up till April 5th, if you average it out, he only got 29.6% of the vote.
That's not exactly a sweeping endorsement, and it's clear if the GOP had pitted one very strong candidate against him from the start, he wouldn't have come anywhere close to winning.
As it stands, the Republicans' taking too long to get their crap together is what caused him to get the commanding lead he had, and now it's just over.