Why small sided?

A very simple answer - small sided games mean more football and more involvement in the game. It maximizes involvement in real football situations.
 
  • More goals, shots, saves, passes, dribbles, tricks and tackles
  • PLAY football to learn football
  • Easy for coaches to observe where players are in their development
  • All players attack and defend in a game rather than being stuck in one position
  • More freedom to explore the game
  • MORE FUN!
 
 “As a coach, I like five – a –side because it’s easy to organise and it develops all the qualities that are important to the modern game. It’s fast, so it improves your vision, agility and movement and because you touch the ball so often, your technique improves too. Today, every player should be able to defend and attack so this game is essential for player’s development.”
Arsene Wenger
 
“In an eleven- a-side practice game, a full back will intervene against a winger an average of seven times. In ‘reduced- space’ football, they intervene 14 times and in a shorter time span. A striker in a practice game will have, on average, seven clear scoring chances; in ‘reduced’ football it is 30.”
Manuel Pellegrini , now coaching at Real Madrid, explains in an article in the Champions magazine his philosophy and why they never play 11v11 in training, but how all his tactics are worked out in small sided games of 5v5.
"We built Liverpool's training on exhaustion and recovery with little areas of two-a-side, three-a-side and five-a-side in which you work like a boxer, twisting and turning. Training was based on basic skills, control, passing, vision, awareness."
Bill Shankly, ex Liverpool manager on training
 
“Liverpool practiced small-sided games every day and it was high-intensity stuff. We used to do a very light warm-up, jog around the field a couple of times to loosen the limbs, do a few stretches, put the cones down for goals and then go into five-a-side or eight-a-side.
It was the same every single day. There was no tactical work, none whatsoever. All the strategic stuff was done within the small sided games. Liverpool believed that everything we faced in five-a-sides would be encountered again on match day. That was why the five-a-sides were so competitive. Liverpool’s training characterised Liverpool’s play – uncomplicated but devastatingly effective.”  
“Practising on smaller pitches, Liverpool were always going to play a short-passing game. We only trained with small goals so there was little long-range shooting. We passed the ball until we got close enough to score. The philosophy centred on passing, making angles and one-touch football.”  
John Barnes, ex Liverpool
 
 He (Bill Shankly) introduced a new fitness regime including diet assessment and skills training. He also brought in the five-a-side games that were to define his and Liverpool's football pass-and-move philosophy - a creed taken from the matches played by the miners of Glenbuck
Ian St John on Bill Shankly (The Daily Record 16th Dec 2009)