OK, heres Chris' notes on the impact of sides for players.
I am still seeing teams playing irregular positions, thats fine, but here you can read the impactthat has.
Here's what the code says/does:
Players have sides they are good at, out of L(eft), R(ight) and C(entre). These are listed in the roster under "Prs" (Prefers). So a player who can play Left or Centre has LC listed. Just Right will be R listed etc.
In the teamsheet as well as a postion (DF, DM, MF, AM, FW) you add the side they will play on (so DFs become DFL, DFR or DFC) and there is no specific limit to which sides folk play on (so you could have 3 DFLs I guess).
When calculating player stats/contribution to the game, the engine checks for Balance: how well do your sides match.
For each major location (DF, MF, FW), *** with AMs and DMs counting as MFs ***, balance is checked. The numbers on the L, R and C are compared. If there are unequal numbers of lefties and righties, a performance adjustment is calculated based on -25% * (difference in numbers/sum of numbers)
So with 1 Left and no right, adjust is -25% * (1/1) = -25%
With 3 L and 1 right, adjust is -25% * (2/4) = -12.5%
etc
If there are just 4+ centre guys and no left or right (eg DMC, MFC, MFC, MFC, AMC) then the adjust is a fixed -13%
This is done, as I mentioned, for DF, MF and FW, so there are potentially 3 adjusters, one for each major location. These adjusters are applied to the major stat (Tk for DF, Ps for MF and Sh for FW) of all the players in the location (so AMs and DMs only count as MFs and only their Ps will be affected)
These effects are noticeable! 25% off a 10 rated DF brings his (and all his DF colleagues!) down to 7.5 tackling.