Now at lv11, I ‘ll give my opinion about sa I ‘ve met so far in TM - scout/list players or to players I gave some of them.
GK
PS-Penalty kick stopper : Useless, very few are the penalties on the game. Maybe somewhat useful after extra time in knock out rounds in CH.L. or Cup but still don’t know if it really working.
OS-One-on-one stopper : If I have a fast trainer GK, I like to give this sa. Seems that's working a little.
Defenders
DW-Defensive wall - AD-Aerial defender
I give my defenders only those two sa because I believe that other sa as free-kick or corner specialist need also to give skill points to attack but I prefer not to.
My fast trainers (defenders), usually are very good performers so I believe that this maybe helps a little. Same for scouts. I buy scouts DC-DR or DC-DL with those two sa only.
Also I prefer those sa for my DMC.
MC-ML-MR
DR-Dribbling specialist : WOW, a dribbler ! Well, I don’t know what exactly a player with this ability is doing. In the beginning I believed that he would do this thing we read in the comments “pass one, then another …” but no.
It's very rare.
PM-Playmaker : Another sa which I don’t know what it’s useful for (surely the player doesn’t give assists). Maybe if he was a basket ball player.
I 've read posts saying that a pm improving the passing efficiency, gives some extra % in ball possession but for sure it's not the assists we 're waiting for him during the game.
FS-Free kick specialist - CS-Corner specialist
Useful sa for MCs but only if it’s working. Also noticed that maybe it’s working for one season and might not working for the next season. Also depending from the form of the player.
Also useful abilities for AMC-L-R but for them I prefer
SS-Shadow striker , when it's working, it's superb !
One-on-one scorer – I prefer this one for a ST (but also a free kick specialist is good).
If a ST doesn’t have this style of playing or he is out of form or he isn’t a good player (bad program/ doesn’t fit with the team) this can’t help him.
PS-Penalty specialist : Another useless sa. Maybe this thing can boost the finishing skill of player and can help him as F-S.