Has English football cracked the secret to combining sporting and business success? However, as clear front-runners in this year's League (although it's still only November), Chelsea might be proving that it's finally possible for Premier League teams to combine sporting and financial success. How did they do it? Chelsea attributed their bumper profits to rising television rights, commercial deals, and what the club called a "significant surplus on player sales." This last element is particularly important as for the first time in many seasons Chelsea sold outgoing players for more than they paid for them (see chart). Buying low and selling high is nothing new in the world of football; it's a tried and tested strategy for most of the league's smaller clubs when big sides come calling to poach their talent. The difference with Chelsea, however, has been that their sales don't seem to have had a detrimental impact on the quality of their squad. Arguably they may have even helped it. The Blues spent a healthy £91.3m in the transfer window this summer, but managed to recoup £85.2m in sales. In generating revenue on footballers considered surplus to requirements, and strengthening the squad by purchasing a smaller number of quality additions, Chelsea can finally boast the balanced books they have long aspired to. Can it last? If Chelsea hopes to sustain profits in the long-term, they may have to look at either expanding the capacity of Stamford Bridge or moving to a new ground in order to generate higher ticket receipts. However, should Jose Mourino's side manage to scoop up most of the silverware they are contending for this season - as many pundits have predicted they will - their on-pitch fortunes will likely attract more generous sponsors and hefty broadcasting fees. It's this virtuous circle, where success begets success, that is the holy grail for football's elite club owners. What about everyone else? Profitability still remains the exception rather than the rule in English football. Although the biggest Premier League clubs generate hundreds of millions in turnover, profits have always been as rare as quality left-footed wingers (see chart). The introduction of Financial Fair Play rules by European football's governing body should help limit the huge losses big clubs have chalking up for some time. Clubs now have to abide by a "break-even requirement," which will compel them to spend no more than they earn through ticket sales, TV rights and merchandising. But even the biggest teams will find it difficult to meet the new spending limits if they can't manage to make things work on the field of play. Only this week, Manchester United reported a fall in their quarterly revenues of nearly 10pc, a loss they attribute to their failure to qualify for the Champions League for the first time since the mid-90s. United are still the most economically efficient of all the teams in the top flight (see chart above), spending an average of £32.7m per trophy between 2003 and 2014. Chelsea meanwhile have won 13 trophies at an average cost of £67.2m. All in all, the trade-off between business and sporting success is not likely to abate in the short-term. Yet, if Chelsea do manage to wipe the board and take home domestic and European prizes this season, they may well become the model the rest will want to follow.