Complex sentence: Clemens was the losing pitcher for the Astros in game 7 of the 2004 NLCS against the St. Louis Cardinals, allowing 4 runs in 6 innings of work although he pitched well, he tired in the sixth inning surrendering all four runs.
Split into simpler sentences: Clemens was the losing pitcher for the Astros in game 7 of the 2004 NLCS against the St. Louis Cardinals, allowing 4 runs in 6 innings of work. Although he pitched well, he tired in the sixth inning, surrendering all four runs.