Having read the AD, it appears that a relaxation of wear limits occurred for the splines. The splines were to be assessed at "crown", a wear of 2.15 mm was to be the trigger for strip and rebuild. As built, the Spline crown is 2.65 mm. When Crown diminished to .5mm, down she comes. At some point, EASA was convinced the "Wear" values could be "Meaned", allowing some wear resistant splines to proxy for what had been a non negotiable "off the wing" event. This extended the "service" of the Splines on the wing, and may have been responsible for November 4, perhaps.
This stub pipe appears to be approx 15 mm in diameter, so the bits lost off the end were perhaps 3-4 mm in size. These bits cannot in my opinion have caused the emergency. Left to roam in a bearing box is not desirable, but oil flow, seal integrity, and bearing misalignment, causing Spline wear signify a degradation over time. The IP is thought to have migrated aft, to do this, the thrust duty of the integrated bearing was compromised, I think. Again I note the soot on the LP Shaft. The report will make some great reading imo.
bear