Boron jumps

may come out as sludge or lab error or different batches of oil always have a virgin sample run of same lot then comparisons will be more accurate oil companies do and will change or have variations in ther formulas and they will not tell you.
bruce

As Bruce said alway's have a virgin oil sample run. Over what period of time has this happened? What is your sample rate/interval? What I'm wondering is if some samples were older CI-4 spec and some newer CJ-4 spec. Is it possible some of the samples are from older stock API CI-4 spec oil, oil formulations have changed.

Trust the changes are after an oil drain and suspect from different batches.
Would check the new oil, but most likely cause is a change in additive system.
No oil company puts all their eggs in one basket, so Rotella T will have at least 2 formulation options of similar performance but slightly different additive chemistry.(for commercial and continuity reasons)
Also as Micbial says perfomance spec may be improved version