Complex sentence: Since the Black Hawks were not an overly successful team during most of those 17 years, March only played in a total of 25 playoff games, but he made the most of those 25 games by scoring 7 goals, 12 assists for 19 points.
Split into simpler sentences: Since the Black Hawks were not an overly successful team during most of those 17 years, March only played in a total of 25 playoff games. But he made the most of those 25 games by scoring 7 goals, 12 assists for 19 points.