Complex sentence: Cobb blamed his lackluster managerial record (479 wins against 444 losses) on Navin, who was arguably even more frugal than he was, passing up a number of quality players Cobb wanted to add to the team.
Split into simpler sentences: Cobb blamed his lackluster managerial record (479 wins against 444 losses) on Navin, who was arguably an even more frugal man than Cobb. Navin passed up a number of quality players that Cobb wanted to add to the team.