Complex sentence: He continued to battle with Hildebrand for starting duties, and was also first-choice during the team's run in the UEFA Champions League; he also committed several mistakes in home matches, which led to fan criticism.
Split into simpler sentences: He continued to battle with Hildebrand for starting duties, and was also first-choice during the team's run in the UEFA Champions League. Unnerstall also committed several mistakes in home matches, which led to fan criticism.