1/As far as I know, at the time it was the largest winning margin of any 800m Olympic final in history (and yet off such a slow first lap where all eight were bunched together). Since then I think only 2 or 3 finals have had a greater winning margin.
2/With 500m to go, Ovett was either last or next to last, and even at the bell he was in 5th or 6th place.
3/Although on the home straight of the first lap Ovett famously tried to mucle his way out of the pack, he was still completely boxed in at the bell in 5th or 6th place. I'm not sure if any other great 800m runner in history in that position would still have won, and not by half a second. Gaps did open up quickly from around 300m to go, but Ovett still had to judge his pace and pick his time.
4/Despite 2 and 3, Ovett ran a 50.5 final lap, still the fastest ever in an Olympic 800m final (maybe even any major 800m final). He surely also could have ran faster. After the bell he was still boxed and got 'knocked about by Wagenknecht' in commentator Coleman's words. In fact it appeared to severely affect his stride. Being boxed in, he couldn't really start accelerating until around the 300m mark. He was obviously aware that Coe was beaten and he was way in front and relaxed and slowed down well before the finishing line. It certainly seems possible to me he could have ran a sub 50 second last lap if he had to and hadn't been boxed in/knocked about.
5/He beat a guy who ran 1:42 the year before, and would run 1:41 the next year. It shouldn't even have been a contest. Yes, of course Coe choked, but at the end of the day this was a race on the biggest stage, and Ovett won easily. The likes of Said88 have claimed it was a 'weak final', but how many other 800m gold medalists had to beat a 1:41/1:42 guy (or a guy who had already ran almost a second faster than any other human being in history)?
6/Further to point 5, it wasn't a weak final at all, and in particular it was a lot stronger than it might look on paper because it was held in Moscow, at the height of the cold war, and Ovett (and Coe) were racing against 3 Eastern Bloc athletes. Wagennecht and Busse had both beaten Olaf Beyer in the East German trials (Wagennecht also beat Beyer in the 78 East German championships). PBs of the East Germans are misleading anyway because they rarely ran outside of international competition and everything was geared to winning those international competitions. Guimarães, the Brazilian who finished fourth, would go on to run a 1:43.63. Another way of looking at the quality of the final is that both Beyer and Wuycke failed to qualify from the semi-finals - both of them 1:43 men.
I believe Ovett was capable of running sub 1:43 that day. If the pace had been 50/51 I'm not sure it would have been a much different outcome except the times would be all much faster, likely faster than the 76 final. IOvett might even have threatened Coe's WR. A faster final would also have been even worse for Coe because he would still have played safe at the back and would have left it too late perhaps even to medal. Coe lost not because he allowed himself to be boxed in, he didn't, he went out of his way to avoid that by staying off the pace until it was ridiculously too late. A faster final would have resulted in something like this:
Gold - Ovett 1:42.65
Silver - Kirov 1:43.30
Bronze - Coe 1:43:40
4th - Guimarães 1:43.60
5th - Busse 1:43.90
I think Ovett struggled for motivation after this and was never quite the same athlete.