Define performance.
Good rate of climb, good runway performance, fast in cruise. What?
What as pilots we consider good, might not be what the airline accountants want in an aircraft.
BA right now are looking at longhaul fleet renewal/expansion. What role do you think the Chief Pilot will have in the decision? I suggest he will be asked how many pilots he will need for various options and that is it. The bean counters will then plug in that small variable into their spreadsheet and decide.
So the MD90 didn't fit in with Boeings plans, nor the airlines.