Although I share your opinion regarding the quality of the IAF, the actual reasons which led to the loss of more than a hundred combat aircraft and a decent amount of pilots in October 1973 was the Soviet SAMs, their abundance and the lack of ready measures to counter them.
The IAF learned its lessons from the trauma of `73 and in the `82 invasion of lebanon took out nearly 30 Syrian SAM sites and shot down about 100 enemy MIGs, without the loss of a single plane, all during a single day of a well-planned operation.
The quality of the Israeli Air Force is believed to stem from the fact that army service in Israel is mandatory, and only the absolutely best draftees are recruited and trained as pilots. A country is certainly big enough a genetic pool for the fishing of individuals for such critical positions.
The fact that most equipment is U.S made probably plays a role as well.