Leicester was 5,000 to 1 to win the title. (Getty Images)

The miracle happened. There are two weeks left to play in the Premier League season and the title race is over. The champions of England, for the first time in two decades, do not reside in London or Manchester but in Leicester, a city of 300,000 in the East Midlands.

There are so many statistics that emphasize just how mind-blowing Leicester’s title run was, but perhaps the most impressive are the economic facts. The English Premier League is a money game, and it was thought you simply could not win the league without elite resources. It usually takes a massive spending spree to finish just in the top four of the Premier League, and the Premier League title winner almost always has one of the three or four highest wage bills in the league. Leicester City will raise the trophy having spent less on wages than at least 10, maybe 15 other clubs in the league. In the last 15 years, no club with a wage bill in Leicester City’s range has taken much more than 60 points, and the Foxes are likely to top 80 this year.

It is a spectacular and unprecedented story. Players and fans will and should be celebrating. But in the offices of Leicester City, people are surely already working to figure out what comes next. Is there any way that Leicester can escape being a one-year wonder?

One of the keys to maintaining success is recognizing what parts of that success you cannot reasonably repeat. For the Foxes, this means looking at the team’s lineup stability. Leicester rolled out the same lineup most of the year, with Danny Drinkwater and N’Golo Kante paired in central midfield ahead of defenders Robert Huth and Wes Morgan. Riyad Mahrez and Danny Simpson covered one wing while Christian Fuchs and Marc Albrighton had the other. Up top Shinji Okazaki supported Jamie Vardy. Manager Claudio Ranieri’s 4-4-2 tactics are built on these paired player relationships. And, by the end of the season, their interlacing movements and communication were nearly perfect. It makes sense in retrospect that Leicester City dominated the stretch run—none of the club’s opponents could match the functioning of the Leicester machine.

Next year, however, Leicester cannot count on such stability. Not only will the Foxes have Champions League matches on their schedule, but lineup stability is rarely maintained from one season to the next. Over the past six years in the Premier League, there is no relationship between a team’s lineup stability in one season and its stability in the next.

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I measured lineup stability by looking at how many minutes a club’s 10 primary outfield players covered. Leicester City’s primary 10 went from covering 70 percent of possible minutes to 87 percent this year. The shape of the scatter plot shows that rates of lineup stability are not maintained season to season. Last year’s Chelsea team appears at one extreme, as the club that Jose Mourinho rode to an easy league title was beset by injuries, off-years and in-fighting en route to a shocking ninth-place finish to the season.

If you look at the clubs with the highest lineup stability in one Premier League season, it reads a bit like a list of the most spectacular collapses in recent years. It’s not just Chelsea. There is also the Birmingham City side that was relegated after finishing ninth the previous season. Aston Villa’s 2010 team that nearly reached the Champions League and was spared relegation on the final day of the season the next year. Roberto Martinez’s Everton that dropped from 72 points down to 47, and the Chelsea club that fell to sixth in 2011-12.

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When a team depends heavily on a core 10, the players develop familiarity and communication their opponents cannot match, and this can supercharge the club’s performance in one season. But such stability is not something that can be maintained over the long run. Reality will eventually intervene with injuries, down seasons and all the bad things that no soccer team can fully prevent.

So what can Leicester City do? The one top club on the list that offers an intriguing parallel is Tottenham Hotspur from 2011 and 2012. That Spurs club limped to fourth place after being run into the ground by Harry Redknapp. In the offseason, Tottenham lost one of its key stars when Luka Modric left for Real Madrid. While Leicester City may be able to hang on to Riyah Mahrez and N’Golo Kante, there is a good chance the Foxes will need to recover from the loss of a midfield star just as Spurs did. Daniel Levy made a series of purchases to strengthen the team’s spine and offer depth to rotate through the season. Spurs had far less lineup stability the next year, as Manager Andre Villas-Boas cycled through several lineups to support star Gareth Bale and deal with key injuries. But aided by this much improved depth Tottenham ended on 72 points just barely outside of the Champions League places.

That is the sort of qualified success story that Leicester City can reasonably aim for. The history of teams with such extreme levels of lineup stability suggests that if Leicester does not prepare for some real reversals of fortune, next year could get ugly. If the Foxes are to stay at the top of the table next year, they must instead approach the problem of acquiring new depth as a challenge equal to the construction of their title-winning first XI.