Eight years ago today, we didn't yet know that the biggest underdog story of 21st-century soccer was unfolding in front of us. Or at least, we didn't believe it.
On Nov. 9, 2015, Leicester City was third in the Premier League table, one point behind Manchester City and Arsenal, but it was surely unsustainable. Their best win had come against a West Ham team that would finish seventh, and the best team they'd played -- Arsene Wenger's Arsenal -- wrecked them at home 5-2. They were racking up points with one-goal wins over teams lower in the table and hey, good for them. But they had also recently lost in penalties to second-division Hull City in the Carabao Cup.
This was a neat story, but it was obviously going to come to an end at some point.
It, of course, did not.
The Foxes snared a 1-1 draw with Manchester United near the end of November and beat a listless Chelsea in mid-December, but it wasn't until deep into the winter months, with wins at Tottenham Hotspur in January (1-0) and Manchester City in February (3-1), that naysayers (read: most of us) were forced to take the idea of a 5000-to-1 Leicester City title run seriously. They lost at Arsenal on Valentine's Day and then didn't lose again. On May 2, with two matches remaining, they clinched the title when second-place Spurs drew with Chelsea.
It was a one-time-only thing, but Leicester's 2015-16 Premier League run will forever serve as an example that technically speaking, any bright, early underdog run could be sustainable even if the odds aren't good. And with the 2023-24 season approaching one-third done, we still have a lot of surprising upstarts to track. Three of Europe's five biggest leagues all have unexpected leaders at the moment -- Bayer Leverkusen in Germany, Girona in Spain, Nice in France -- while Tottenham Hotspur was the Premier League's leader until this past matchday. (Are Spurs the prototypical upstart? No, but they stunk last year, so it sort of counts.)
Which of these underdog clubs (and Spurs) are ready to put something sustainable together? Which ones probably aren't going to last until Christmas? For eight clubs with particularly impressive early surges, let's create sustainability scores.
We'll use two primary categories, scored on a 1-5 scale. First, we'll look at the underlying stats they've produced to date -- xG figures (which are more predictive than simple goals scored or allowed over time), close-game performance and other things -- and whether they suggest legitimacy or, perhaps, a bit too much luck. Second, we'll look at the roster itself. How trustworthy are each team's best performers? Can they keep up with what they've been doing?
Add these two factors together, and you've got a maximum sustainability score of 10. So let's talk overachievers!