Complex sentence: The Ligier JS11/15 was an excellent car but the team's incompetence and Laffite's political control of the team meant that Pironi was not going to win the championship with Ligier.
Split into simpler sentences: The Ligier JS11/15 was an excellent car but couldn't reach its maximum potential. A combination of the team's incompetence and Laffite being in firm political control meant that Pironi was not going to win the championship with Ligier.