Son Heung-Min has always been sort of a streaky player at Tottenham Hotspur. While he has improved significantly since he first arrived at the club and has shown immense purple periods of production — take the period between December and mid-January in which he tallied six goals and four assists in nine league matches — Son went from the first of April to the end of the season without scoring.

That cycle has furthered suggestions that he’s a hot-and-cold player, but in this particular case it looks like there was a reason. According to Dan Kilpatrick writing in the Evening Standard, Sonny spent the last six weeks of the season on painkillers, playing through a slight ankle injury.

“I really played a lot this season, but luckily I had no big injuries and gained some experience,” Son said in Seoul. “I did take painkillers for the last six weeks to play in matches, but there aren’t footballers who are free from injury. I’ll take some rest this week, and I’ll be fine.”

You really only have to look at Harry Kane to understand what an ankle injury can do to a professional footballer, especially one who relies on pace and trickery like Son. Clearly Sonny wasn’t injured enough to miss significant (or any, really) game time, but even a slight injury could make a player think twice about making that dribble attempt, and even a 10% loss of mobility can make a difference at the Premier League level.

I’m not saying that Sonny being on pain killers was definitively the reason why he seemingly went off the boil since April, but it really could explain a lot. And despite that, he ended the season with 18 goals and 11 assists in all competitions, down only slightly from his tally in 2016-17. Still a pretty darn good season.

Son’s got a pretty intense summer coming up — he’s the best player on the South Korea side that’s playing in this Summer’s World Cup in a stacked group that includes Mexico, Germany, and Sweden. He’s also set to play in this summer’s Asian Games after the World Cup ends, with this being his last chance to win a gold medal and avoid his compulsory military service. Son pretty clearly knows the challenge ahead of him, and said that in the World Cup he’s “desperate” for his country to put in a good showing.