Wha...
so, when Mr Lee ignores the procurement process iot bargain down the price of some generation-before-last jet aircraft, he's a genius, and when John Howard buys inolvement in a project which will see Australia at the forefront of fighter technology for decades, he is an evil despot?
Similarly, when Brendan Nelson ignores the normal processes to buy F-18E he is a criminal moron because F-111 can still cut it...oh wait, no, he's also a genius just like Mr Lee, but ....
wait, aren't you just talking bollocks, TBM?
If it was easy, or intuitive, then ex-FLTLTs would be hired back on contract to make these decisions and win the day. It isn't easy, and there are a bunch of competing priorities on every project, so it often goes wrong.
Buying FMS, (which is different to COTS and MOTS) is the only option for limiting technical risk - except when the US is already up to it's neck in technical risk (JSF). In any case, it just transfers our risk to the US military.
The only thing you can safely say is that buying old, last-generation military equipment is less risky than buying new equipment. Whether or not that equipment meets the requirement is another question entirely.