There are indeed two ways to qualify but you are mixing concepts:
- 50 flights, but not on any OW airline. The only flights that count are either OW or VY flights with IB code, flights operated by IB/I2/YW, VY flights with VY code not on Basic fare or flights operated and marketed by BA.
- 2250 Elite Points with at least one flight with IB code operated by IB/I2/YW/VY/BA.
For example, if you fly JFK-LAX on AA it will give you Elite Points but it will not count as one of your 50 flights.
This is for Oro, Plata (Ruby) is just 25 flights or 1200 points.