Devonish and team-mates Mark Lewis-Francis, Darren Campbell and Jason Gardener shocked the world with gold in the Athens Games in 2004 - and he explained just how they did it.
"In 2004 our flat speed was not equal to that of the Americans and Jamaicans, but we won gold because we were both fast and smooth. That's the beauty of the relay: it's not just about flat speed," he told Eurosport.
"It isn't about the athletes' individual speed: it is about the baton's speed around the lap. If you looked at a graph of the baton speed for us in 2004, the line would be consistent whereas for the Americans, it is all peaks and troughs. Peaks when they run their leg; troughs when they change over and their speed goes right down.
"If you have poor baton skills it leads to a decrease in speed. Bang! The changeovers have to be seamless.
"The event has moved on since we won gold in Athens. People are running quicker but also the faster teams are more aware that the changeovers are so crucial to the outcome."
The defence of that title in Beijing lasted as far as the heats when Devonish's changeover to Craig Pickering was carried outside the designated box - the same fate to befall Team GB at the current Games.
And the sprinter, who missed out on his home Olympics through injury, said that this is always a danger even for the best-drilled teams.
"You can use your check marks to set off at the right time, but what sometimes goes wrong is that it is impossible in training to replicate 80,000 people," he said.
"You hit the mark, but the adrenaline makes you quicker than normal and you get too far ahead of your team-mate. And you have such a limited time to pass the baton."
Team GB failed to make the final in London after 21-year-old Dan Talbot and 18-year-old anchor man Adam Gemili strayed beyond the allocated changeover box, with Gemili also running out of his lane.
Yet, despite the disappointment of seeing his nation crash out of the competition, Devonish is adamant it is those changeovers that make the relay races such compelling viewing.
"The event is special for the fans because the changeovers make it so exciting," he said.
"If you get it right, it feels like the best thing in the world; if you get it wrong, you are a failure. There is no in between - and I have been on both sides of that coin."
Marlon Devonish was speaking at the Mizuno Performance Centre - open to the public between the 24th July and 12th August at Centre Point Building, 101- 103 New Oxford Street. Visit www.mizunoseiei.com for further details.