It was a battering. You can try to mask it all you want. Nelson deserves credit for surviving, but realistically it was JDS smashing him for three rounds. Nelson's only real hope was a massive haymaker (which he kept trying to throw) or taking Dos Santos down (which he failed massivley at). JDS was just too quick and much better conditioned as well as being on a completely different level technically.
I watched the fight back last night. I have no idea when you last watched it, or what you consider a battering, but to me, you're exaggerating far too much. If I hadn't seen the fight, I'd think JDS wiped the floor with him, was unscathed and just as sharp in the last round as he was in the first. None of those things happened and the pace and impact slowed considerably from the first to the rest of the rounds - at the pace of the 2nd and 3rd rounds, Nelson always has a chance and that was evidenced by him tagging JDS and backing him up at times as well as the cuts to JDS right cheekbone and his bruised nose, which tells you he was in a fight and took damage.
It led to Joe Rogan saying that this will prompt JDS to understand he can't just go in and take everyone out in the same way and to learn (or utilize) more variety in his techniques and to kick a hell of a lot more. He also made the point, in the 3rd round no less, that despite JDS winning the fight on points, Nelson proved to be one of the most difficult opponents he's faced due to his sheer resilience.
By the end of the fight JDS looked quite exasperated, which made him cautious of going in to finish - it was in no way as one-sided as you've made out. The first round was the explosive one that fits best with what you've said, the other two favoured JDS, but were not a cakewalk (as he got tagged in both, more than once).
It wasn't even really a contest and Nelson is hardly a better fighter now than what he was back then.
Nelson is much smarter and less linear. He picks his shots better and times them better. He is clearly a better, smarter fighter now than he was then.
By points, JDS won comfortably, but to say it wasn't a contest would suggest that at no time was JDS in trouble, which is simply not true.
Dos Santos has good enough take down defence to stop Nelson taking him down and that leaves Nelson with one hope which is landing a big shot. JDS has also shown he can take a shot and shrug it off. Not even comparable and there'd be no reason what so ever to ever book a rematch between the two. JDS is without a shadow of a doubt a better fighter than he was then too and
My issue with what you've said is that you're suggesting JDS has, and had, no problems at all with Nelson to the point of it being a non-contest, when that's not what happened and wouldn't happen if they met again.
As I've already said, JDS would win on points if the fight went the distance, but in the 3 rounds before the scorecards are pulled, Nelson would definitely have opportunities to win the fight, and not just in the hapless way you described - he caught JDS with a nice one, two, in the 1st fight, which is sound technique and not just some donkeyish hit and hoper.
I still have him ahead of Cain and am confident he'll get the title back when they meet again.
If he can't tag Cain, what happens then? What does he fall back on?