Keino's gold WAS tactical. He was something like 0-49 against Ryun prior to that race, and Ryun hadn't lost in 3 years.
Keino had tried everything: Going from 100, 300, 400, and 600 and various races, and none paid off. Finally in Mexico City he decided to take it from the bell. Ryan still closed in 54 high that day, and had Keino not gotten out so hard (54-something first lap!!) Ryun still may have prevailed.
Lots of arguments both ways: Ryun had mono prior to Olympics, while Keino had the advantage of training at altitude. But few remember Keino's difficult Olympics up to that point. He had severe pain from a gall bladder infection and already had a 10,000m and 5000m in his legs (although he was DQ'd after finishing the 10km as he had laid on the track with two laps to go due to the stomach pain). Then something happened with transportation and he had to run to the stadium on the day of the race.
Ryun actually calls that race one of his best ever. It just so happens that Keino ran potentially the greatest 1500m race ever.