Numpty >>
friday october 18 - 08:37, Edited
friday october 18 - 08:48 The simple answer is that we don't know.
The game says better or worse for a quite a few of the specials, some say "small bonus" or other similar wording - but no-one seems to know exactly what the numbers are. So in order to make an estimate we may perhaps get a guide from considering the wording of those that do mention precise amounts.
As far as I know the original specials mentioned amounts of 1 ball - and then Playmaker got downgraded to 0.5. So any unspecified amount is likely to be signficantly smaller than 1 ball extra. Otherwise why not say?
Other specials (that I think came later) such as Poacher and Versatile mention smaller values of +0.25, -0.3, -0.15 etc.
On that basis I would estimate that any unspecified bonus (or penalty) in the original descriptions are likely to be in the region of +0.25 or less on the primary or on all trainable attributes.
As to how to use a supersub forward it depends on what alternatives you have. Bringing him on in the second half is the best choice if you have a reasonable 3rd striker who can start the game.
Kalle's suggestion is also useful, although as you say it affects the xp. May be a good idea for cup matches though - and also during the second half of the season when the player going off has played all his 20 matches for xp.