It was not so much the many blows he received as the lack of fighting spirit that led to his losing the game.

本句为It was...that...强调句型，强调主语。

主语由准并列连词not so much...as...连接，即并列的二个名词词组，通过比较后否定前项，肯定后项，意为：不是A，而是B。与其说是A，不如说是B。

his losing the game 为动名词复合结构作led to的宾语。

句子译文：与其说导致他比赛失败的原因是他受到的多次打击，不如说是他缺乏战斗精神。

正是他缺乏战斗精神，而不是他受到的多次打击，导致了他的失败。

该句可以改写为：

It was the lack of fighting spirit rather than the many blows he received that led to his losing the game