Complex sentence: During the 2014-15 season the team started strong but as they progressed the club started having financial problems, having had to declare insolvency, and that affected the team negatively resulting in a period of poor performances.
Split into simpler sentences: During the 2014-15 season the team started strong but as they progressed the club started experiencing financial difficulties, having had to declare insolvency. All of this affected the team negatively resulting in a period of poor performances.