I don't know about the most breakable rider in the current peleton. I do know that a former training partner of mine (a domestic US pro) had a series of injuries that were pretty grim at the time, and pretty hilarious now.
On a training ride, he grabbed the roof rack of a support car we planned to motorpace behind. When the light turned green the car accelerated, but my training partner was daydreaming. He suffered a dislocated shoulder and was twisted on the saddle in such a manner that his vas deferens became tied in a knot. By the evening, his testicles had swollen to about three times their normal size.
We had gone to the emergency room for an x-ray of the shoulder earlier in the day. We had to go back to see the pee-pee doctor. A minimally invasive surgery was scheduled for the next day, much to his relief.
Four days later he was commuting to class on a track bike and got hit by a school catering van, suffering minor rash and bruising. This crash made the front page of the campus newspaper, complete with a huge photo.
Two days later, he decided to cross the yellow line in a county-line sprint and was hit from behind by another car. I will never forget seeing him skid along the road in front of the car (which had slammed its brakes on by this time) with is hand on the front bumper. This crash led to some major rash on the side opposite the rash from the crash on campus.
So there you have it. In one week he rashed both sides of his body, dislocated a shoulder, and tied his balls in a knot.
He went on to have a great career, representing the US at the world pro championships about a half dozen times.
I found a new training partner.