Complex sentence: Halfway through his senior season, he had rushed for almost 1,000 yards and was a leading Heisman Trophy Candidate, but a turf toe injury in the latter half of the season substantially affected his performance and caused him to miss one game and most of another.
Split into simpler sentences: Halfway through his senior season, he had rushed for almost 1,000 yards and was a leading Heisman Trophy Candidate. A turf toe injury in the latter half of the season substantially affected his performance and caused him to miss one game and most of another.