For me it was the 2016/17 UCL top scorer battle. After the round of 16 ended, Messi was the favourite to finish the season as the top scorer, with 11 goals in only 7 games played. At the same time Cavani had scored 8, Lewandowski and Aubameyang had scored 7. Meanwhile Ronaldo had scored only 2 goals until the quarter-finals started, even his teammate Morata had scored 3 and he only started one game in the competition.
Flash-forward to the end of the campaign and Ronaldo finished the season with 12 UCL goals, after his brace in the final to help Real Madrid in their 12th (then) UCL trophy. A truly iconic turn-around that isn’t talked about much in my opinion. Any other suggestions?
St Mirren 2016/17 season and then 2017/18 season.
At the start of the 2016 season St Mirren Alex Rae was in charge. We didn’t win a competitive league fixture under him that season. He was sacked in September. At the start of October, former Saints player Jack Ross was appointed manager. We wouldn’t go on to win a game till the start of December, with a stoppage time goal from Stevie Mallan. We were 6 points adrift at the bottom of the table.
There was a significant turn around in performances following the January transfer window (with a challenge cup game against The New Saints often being cited as a turning point in the season). In the end it too until the last day to secure safety with a 1-1 draw away to champions Hibernian.
The following season in the league we started with a win, a sign of things to come. We would go on to win the league by 12 points, defeating every team in the league at some point.
Going from last day relegation escapees to champions the following season was some roller-coaster.