Complex sentence: Kimmel earned a reputation as a hard worker that inspired subordinates, but some criticized that his over-attention to detail betrayed his lack of self-confidence, always spending time to revisit minute tasks he had done previously when he could have delegated the work to others.
Split into simpler sentences: Kimmel earned a reputation as a hard worker who inspired subordinates, but some later criticized him for over-attention to detail, claiming it betrayed a lack of self-confidence. These critics asserted that Kimmel constantly revisited minute tasks he had done previously when he could have delegated the work to others.