I think it is pretty widely recognized that his staff isn't experienced, and there are very few of them compared to a usual campaign. If you don't agree, I understand that we are talking partisan politics, so I'm unlikely to convince you.

Perhaps consider listening to some political wonk podcasts and you hear how amazed they are at how the convention was run. Things like calling Fox during one of his speaker's speeches, not knowing what multiple speakers were saying, and the whole thing with the VP rollout: http://www.vox.com/2016/7/15/12199676/trump-vp-pence-rollout

Mitt Romney's convention was nothing like this, nor was any other convention from either side of politics.

It isn't really surprising - he isn't exactly from the core of the Republican party, so he hasn't been able to rely on people just doing what they always do. That's a quite reasonable explanation, but it doesn't deny the facts of his disorganized campaign.

Now it may well work out fine - a lot of things that people thought were important are tuning out not to be.