Thanks to La Canadienne for this one. We collectively racked our brains over this word for a little while before I arrived at my own definition. Whether it’s right or not, that’s another question. Someone French can tell me.
If you listen to French race commentary you’ll have heard the word baroudeur. It’s often used in the description of stages that are very lumpy but not too mountainous, often ending in a descent or at least on the flat, e.g. Stage 14 two days ago, which was won by a baroudeur – Bauke Mollema.
On my first attempt to find the definition of baroudeur, I found this helpful one: “someone who loves le baroud“.
After further investigation, it seems that this is also someone who loves to fight, battle and is an adventurer. Finally, when it comes to cycling, it appears that it refers to a rider who revels in attacking off the front, preferably by him/herself, to attempt a solo win. Think Thomas De Gendt, the modern epitome of Le Baroudeur.
The Vicious Cycle 
I suppose “Breakaway Specialist” doesn’t have the same je ne sais quoi.
Far too literal for the French, I’d say.