Looking back at it, Stannard really fooked up.
Watch the final 'sprint'. Try telling me one of them was anywhere near full speed. It was basically who had the most left in the tank.
It was clear that Vanmarcke was the strongest on the cobbles thanks to the Mons-en-Pévèle. Therefore, attacking on the Camphin-en-Pévèle was a mistake. He was unable to drop Boonen and EBH as well as Vanmarcke, and after riding on the front for over 1km, he got torched by Vanmarcke's attack on the Carrefour, where he decided to pretend he was weak and hang off the back. BIG MISTAKE. Luckily for him, it didn't cost him, as the four riders co-operated well to bring back Vanmarcke who simply wasn't strong enough to stay away.
Next, fast forward to 5km to go. At this point, you had a strong Boonen who simply wasn't letting anything go. (ie you don't want to be the first man to attack and waste energy). He was riding for the win - 1st or nothing. Therefore he was gonna chase anything down if he could. Then you had Vanmarcke and EBH, who would contribute if needed. Finally, you had Hayman, who was always going to be the least marked of the quintet.
So, Stannard's attack with 5km to go was never gonna work. MISTAKE #2.
Finally, it was clear that if you did attack, the best time to attack was after a Boonen attack, as he was always gonna be the main chaser. If Boonen never attacks, you never attack too, and just wait for the sprint - everyone is going to be tired.
As it happened, when Boonen attacked, Stannard was caught out, and although him and EBH were able to bring it back, with Stannard being there for the final sprint, a) he was too far back because they joined too late, and b) he wasn't quite strong enough, because he wasted too much energy beforehand. I truly believe Stannard would have won that final sprint otherwise, especially given the amount of work Boonen had already done in the day, and that Vanmarcke was always going to commit to a move on the Carrefour, while EBH wasn't strong enough, and let's face it Hayman was in the break for a long time.
However, it must be said that until 20km to go, he rode an absolutely perfect race, letting others do a lot of the work and conserving a lot of energy.