Not all installation "losses" actually degrade thrust. For example, at takeoff N1 with no IDG or CSD or hydraulic load, the thrust is XYZ which is the sum of fan and core nozzle thrust.
If you then add on the gearbox loads, turbine temp (EGT or ITT) must rise at the same N1. The result is the core thrust INCREASES for the same fan thrust, and the total thrust is thus greater than XYZ.
