In each line of the formation, there are 5 spots that players can placed (L, CL [center-left], C, CR [center-right], and R). However proficiencies are only given for 3 spots L/C/R, and only central players (C) can fill the 3 middle spots without penalty. I think that wing players (L or R) should be allowed to be played in their respective center-wing (CL or CR) positions without penalty, or with only the tiny penalty (2%) equivalent to "accomplished" rating. Similarly, playing a central player in either the CL or CR positions would give them the same slight penalty unless they are proficient in both central and wing positions.
For example, imagine a ML (or AML, DML, DL) player without any proficiency as a central player. Currently they can only be placed in the following positions (X) of the line without penalty:
X O O O O
Instead, IMO the L player should be able to be played in the following positions (X) without the regular penalty:
X X O O O
...and similarly for the right (O O O X X rather than just O O O O X).
Central players would still have the most flexibility as to where they can play (3 spots without big penalty), but with such a change, we would get a bit more flexibility with wing players with 2 spots, rather than just the 1 they can be played in without (significant) penalty.
More importantly, L and R players should interact periodically with MR and ML players at the very least, which does not seem to happen in existing match engine
