Well, it depends how many boosters you can have.
This season I 'm going for the treble with a basic squad of 11 + 3 players in the bench.
The key is to create some players with 3 positions
- like Baxter playing 3 positions in defense
WALLACE - add him another winger position
and Croydon, a DC-DMC-MC
also I found two more (market) players who had triple role , GILES and Khama
Also you can find some good players in the market or in nego list , ex-scouts or ex-recommended players (if you want to keep a small roster, it's worthy to spend some more T for them).
With 4-5 players you can cover AM & ST positions.
With my other team, NIK also playing with 11 +3.
If you have a small roster. you can develop more those players (as they're participating in more games).
Injuries now is a lot less and if you heal a player, you know that he 'll be ok for the next 10-15 days so it's only the problem with the cards.
So we can go also with 7 1* players +the 2* academy player. There is a risk the first day, if you have some active opponent in the cup and you didn't find some players to fill the 11 squad.