Here is the history of the #2 engine prior to failure from the ASTB report:
he No 2 engine was originally fitted to the aircraft in the No 4 engine position during aircraft manufacture, and was removed from the aircraft on 12 August 2009 due to metal being found on one of the engine’s chip detectors.16 That removal took place after 3,419 flight hours and 416 cycles.
In September 2009, the engine was sent to a workshop in Singapore for examination and repair. That workshop was certified to maintain and repair Rolls-Royce plc engines. Spalling of the top raceway of the low pressure compressor location bearing was identified and the bearing assembly was replaced. The repair was completed in December 2009.
The engine remained in storage until it was refitted to the aircraft as the No 2 engine on 24 February 2010. The engine had completed 2,895 flight hours and 261 cycles since that re-installation.
On 24 June 2010, Rolls-Royce plc Service Bulletin RB211-72-AG329: IP Shaft Rigid Coupling - borescope inspection of the coupling splines was carried out on the engine. That inspection was mandated by EASA AD 2010-0008 dated 15 January 2010, which was subsequently revised by EASA as AD 2010-0008R1 on 4 August 2010.
Take a look at the engine parameter chart again, you may want to print it out to see it better. The bottom graph is title "oil quantity", not "oil chemistry".
IMO, I think it more important for the ground mechanics to know that metal has been detected in the oil after each flight, or not, as is the setup on the A-380's. Chip detectors are there to signal the existance of wear in one or more of the bearings and it is up to the ground personnel to investigate and locate the source, not the flight deck crew. Think about it.