Plus/minus is a regular thing in hockey and its utility can be traced back many years.
However, it's used to display how effective a team is while a certain player is on the ice; the fluid substitution system employed by that sport demands a similarly versatile but telling measure of player and lineup efficacy. The system has its drawbacks - especially in sports such as basketball - but it remains a useful indicator of a player's performance within a team's dynamic.
The plus/minus method of player evaluation has yet to be used in football with any regularity. This is partly because the analysis is just beginning to see widespread use across the sporting landscape. Applying it to football - where substitutions are marked, fixed events in game timeline - rather than the constant back-and-forth of a hockey match also makes its application curious in this setting. This means that a regular substitute - Ole Gunnar Solskjaer for example - has far less time to influence a contest than a goalkeeper like Gigi Buffon and his plus/minus statistics would take on less meaning.
Plus/minus works far better when it's applied to an individual both in gross terms and on something of a per-minute basis. For our purposes a gross plus/minus figure will be listed, alongside an adjusted total which shows how frequently a team scores/concedes when that player is on the park, parsed out over a full ninety minutes.
Over the course of the English Premier League season 2013-14, Plus/Minus stats for five clubs deemed as most interesting will be recorded and updated weekly; those teams are Aston Villa, Cardiff City, Manchester United, Southampton and Tottenham Hotspur. What they tell over the course of the season remains to be seen.