Nothing is certain unless you sat in the decision making meetings. (I did not.) But a few things to keep in mind that would have forced lists to include stronger performers.
1) Age distribution of group - NRE and retirement eligible were excluded, so a group with more experienced folks has to dig deeper into the higher performers to meet the same cut
2) CL - each organization chose what range was in scope, F&L was 26 or lower while GP went through at least 29. Also included in this one is how the cuts were distributed - across the entire pool or same % to each CL bucket.
3) Skills vs future needs - yes, this one is more subjective but look at where we are heading as a corporation in terms of investment, all roads lead to Upstream (for investment) and outsourcing (for service functions - supply chain, sales, project management)
I'm sure there are other criteria, but just a few to show how performance may not have mattered as much as it appears.