Voted striker and right back based on assumptions:
1) Cushing becomes manager and maintains the 3-4-3 used at the end of the season.
2) Only two of the three major free agents are retained - Callens and Johnson.
3) Santi is acquired permanently.
4) Maxi plays for one more year.
The team is set at wing, but needs a true striker. Magno has all the promise in the world, but Heber opened up the offense with his movement, running channels and pulling the defense. Unfortunately, Heber is on the wrong side of 30 and is best used in a rotation - 35% in a 65%/35% split. Thiago/Magno?Gaby at wings, Heber/???? at striker, Santi/Maxi at the 10 (moving to wing as the situation requires).
With respect to RB, I have a feeling Tinnerholm is the most likely not to be re-signed. Even if he is, right wingback is the weakest position with respect to depth (sorry, Jasson). At LWB O'Toole and Pellegrini (with a full off season) should be fine, or even good. RWB, though, is thin.
At CB I expect Callens to re-sign. Callens, Chanot, and Martins can be the primary CB. Haak and Gray can start the season preparing to replace Chanot when he retires. Gray is more of a CB than a RB, and Haak can spend the off season lifting weights - between the two of them, it is a fair bet that one can improve to become a key starter.
A midfield option is needed for depth unless Zelalem is trusted. However, the need isn't as pressing as the above. Morales should have one more year, Parks will hopefully be healthy, and Acevedo blossomed at the end of the year when he was the only option. If Santi is retained, he becomes the natural heir to Maxi. Haak and Zelalem might be rostered options, but I could see a Rocha level replacement signed. Spend the big money on striker and RWB.
Of course, if we lose more free agents, Santi leaves, or Maxi retires this plan is a wash..