"One was the way Stuart Broad got his tail up with those wickets in a clump [reducing New Zealand from 251 for four to 251 for seven on the second day].
"If we'd pushed that lead on beyond 300, who knows? And when Foakes came out, if we'd got another wicket we knew there was a longish tail.
"This morning was always going to be tough with an old ball [15 overs short of a replacement] and obviously Joe was key as a player who's got England out of past sticky situations."
Alternatively, Root pinpointed a 17-run over blasted by skipper Ben Stokes on the second day.
"That over [the 49th] against Ajaz Patel was a big moment and it was smart of the skipper to take him on like that to shift things back in our favour."
Root has scored 26 test centuries, but this was his first in a fourth innings.
The 31-year-old said unshackling himself from the captaincy helped.
"I had developed an unhealthy relationship with the role. It had started to take a toll on my personal health and I couldn't leave it at the ground anymore. It was coming home, and that wasn't fair on my family.
"I was determined to help turn this team around, but I realised it needed to be in a different way."
In further concerns for the Black Caps, the top four only mustered 50 runs from the match and a moon-booted Colin de Grandhomme looks set to exit the tour with his right heel strain.
Captain Kane Williamson offered a phlegmatic response in the aftermath. He says they were hoping for more swing from overcast skies.
"A lot of guys have played in England before and talk about overheads and today you couldn't have hoped for much better. [Our challenge] was met with real quality in the batting chase.
"The match was finely balanced and we struggled to get any assistance, plus we were met by that exceptional knock from Joe."
So Southee and Williamson, two incumbent New Zealand greats, were left to endure another test loss to England among other near misses at the ground across the formats.
Southee said the latest duel still marks a bright spot for the New Zealand game, because they're in demand as world champions.
"Sitting on the balcony the other day I said to Kane there are 30,000-odd people watching this test, which makes it a special place to come and play."
Meanwhile, the finger is getting pointed at cows failing to show enough resilience despite their obvious commitment in the manufacture of balls.
Pundits have been claiming the finished products from the Dukes brand used in England are softer than in the past, meaning the leather bruises quicker and the balls lose their shape.
Southee said opponents Stuart Broad and James Anderson have been telling him likewise.
"Historically it's been a good ball but normally a bit harder. I don't know the ins-and-outs but we had a number of changes, so there's obviously something going on there."
