#2 Luck
A study by ESPN showed that Liverpool was the unluckiest team last season in the Premier League losing 12 points due to 'wrong' decisions. Though it would have still left them 10 points behind the runaway winners Manchester City, they would have at least closed the gap.
Liverpool was awarded just three penalties last season which was five less than the season before. A bit more favorable referring decisions and constant luck throughout the season would certainly help their cause.
Injuries are another area where the Reds didn't have the best of fortunes last season. The cruel knee injury to Alex Oxlade-Chamberlain was a significant blow to Jurgen Klopp's side. A bit of luck with injuries and refereeing can certainly boost their chances of a Premier League glory.