Kind of a touchy topic there, as there were stereotypes of Sephardic and Mizrahi Jews being poor fighters and relegated to rear eschelon roles in the IDF. Of course, a lot of it was simply racist bullcrap, and Eastern Jews performed quite well from the '67 War onwards in the IDF (and nowadays, it is not uncommon for even the elite units to be mostly made up of Mizrahim or those from the National-Religious Sector while the secular Ashkenazi have seen increasing rates of evasion of service).
A lot of the issue was a culture clash in that the IDF was organized along European lines with ideas like autonomous initiative taking junior officer corps being built along German lines, with armored units and the air force based around American doctrine of combined tank-artillery-aerial integrated communication, and the elite units taking much from the British Commandos. They generally faced Soviet esque Overcentralized armies that placed a lot of emphasis on overwhelming the enemy with men and machines on a front wide basis, and this fell apart once the air battle was lost and lines of communication were imperiled, leading to disasters like the retreat to the Suez Canal in '67 or the failure in the Golan Heights in '73. There were even racial issues among the Mizrahi, where the Moroccans and Iraqis were treated like garbage while the Yemenis and Algerians were seen as quite good.
Israel likely could have won the wars after 1948 without Eastern Jews, as they won not because of manpower but because they faced incompetent enemies and won the air battle early and decisively. But the Arabs of 1948 were hardly even nation states, with the best unit, the Jordanian Arab Legion, led by British officers, and the other units deployed half heartedly and not coordinated at all. That has little to do with manpower and more to do with incompetence.