I think it's easy to come up with all these "should have done" arguments, but I bet that the actual options left in the suitcase of courage, 200+km into Roubaix, more pave and headwind ahead, and a Swiss rider who has been reigning supreme during the entire cobbles season, will seriously mess with what people can muster on the last 50kms.
In other races, groups are often the sum of its parts, but I can think of few Roubaixs where any group was more than a sliver better than the strongest legs present. And today, the sum of those legs was thundering off into a galaxy far far away.
I don't think that Boonen was that stupid to attack as often as he did, just before Cancellara went. Boonen didn't jump to escape, he jumped to dwindle. He felt isolated and wanted to even things out, by reducing the amount of riders that still had team members with them. He has frequently done that and it usually has worked out reasonably well, even in the very recent past. If he had succeeded and had indeed been the last one left with Cancellara "as before", we wouldn't question that strategy one moment. We probably would even applaud him for racing strongly.
Looking back it is easy to see Boonen's moment of weakness in glorious HD. But up until earlier this afternoon you would have been told to get your head examined if you suggested that anyone would stupid enough to jump away at that point in the race, into that wind, with shy of 50k left on the clock. After his pave attacks, he went back to check the damage, and it was substantial. Boonen had some food, all good in any normal race, and then was caught out by someone who actually felt about another 20k stronger than most of us thought on the limit of super bloody brilliant already.
So today he was super bloody brilliant and a half. I've tried to imagine what the thought process must have been, when someone find himself ith 50k of Roubaix and wind ahead, and decides that moment there is "the perfect time to go", and not 20k later. From that group. I'm still giggling.
And since this is PR, they all know that the strongest legs do win here, they know their own legs, they see what sits around them, and whose race the 2010 edition was. The very moment he went, after those first 50 meter he took, I think everyone knew exactly they had all been reduced to also rans, at a point in the race when their head was dealing with totally different things. The "normal" thing to expect. No-one seemed too sure how to handle that. I don't think this was an endgame anyone was ready to face, or able to face.
What you saw for a long while was a group that bit by bit comes to the realization that it is indeed game over, and that they have 40+km to go. No-one too sure what that means for the rest of the race. All of these have riders have "lived" PR, as a legend and as a race. And none of them had been in anything remotely like this. They all knew what to expect, and still didn't know what hit them.
We're 200km into Roubaix. And it might not have been wet, I have heard many riders say this was a particular tough one. Some said that in this one, the paves were actually the easiest bit, that this time was always gonna be about the bits in between. That hard.
It must have been one hell of a smack onto planet Earth that the guy they all expected took off, 50k out. (feel free to mentally insert that faceplant photo). And you see how people react when they are feeling the effort put in already. By his own account, Boonen even forgot to eat during the part of the race that followed, and he was the stronger one. What does that tell you about the real organisational claw-back capabilities of this group.
It's nice to suggest "if they had worked together" or "x was hiding", but these were already the last few left standing with quite a bit of the race to go. There is no hiding in PR. It is a monstrously tough slow uphill ride that never gets above sea level, and you don't end up at the front cruising on other people's tails.
In most other races, you probably would indeed have seen a chance and attempt to work together and join forces. By people who still have that as an option in races that are less taxing. But "should have" is in no relationship to "could have" 200km into PR. Veterans as most of them are, it must have been one shock to find yourself 50k out and realize that in all honesty, you simply "don't have" what that guy who just left you "does have", today.
I think PR is one of those races where people slowly lose it in many many ways, body and head, and any weakness is exposed and usually fatal. Few groups count for anything in the final stages before the velodrome. We are used to see finals a bit closer to the end, but people always finish in PR where their own legs get them to.
No-one was racing or settling for 2nd that could have been racing for 1st. Not in this race. And racing for 2nd, well, everyone does that differently. Atypically, this time they had a long time to do it that way, fuelling our speculation what they should/could have done, as we had so much more of limbo on display then normal. But I think all the claw-back options were already off the table the moment Cancellera showed what his legs felt like, and everyone knew what that meant for all of them, eventually. And, in PR, inescapably.
Here, those last 48km were always for 2nd, however they were tackled. And no rider gets a top 5 in PR sucking wheels.