This is not raw chicken. It's a little difficult to tell exactly what it is - possibly bone marrow, possibly part of the joint (where the bone is thickest anyway), possibly an unusual blood vessel makeup or some combination of all of those. But, I can say one thing for absolute certain:

No chef would have ever been able to tell that without cutting into the chicken. It was NOT raw, and you can very clearly see that in the meat - not just the outer layers but the pink that you see in the meat is nothing like "raw chicken" pink, it's sort of "some blood or myoglobin". Some chickens are different to others, and we've been sanitised to never expect anything like this, but it's just a fact of meat that sometimes you're gonna get this stuff - and, substantially more if you cut through bones and joints.