I really, really can't disagree with this idea that Gay and Carroll are SFs strongly enough. They are PFs. They both play the same position as Lyles. Maybe off the bench, one of them will play the three, but that likely isn't the goal. I'm expecting the rotation to look like this.
Murray, Mills
White, Forbes
DeRozan, Walker
Carroll, Gay
Aldridge, Poeltl
While we may all want Mills to not have a spot, he's going to get one unless the Spurs acquire a really good forward. Someone like Stan Johnson wasn't going to change that. From what I see, the team has adequate forward depth after this move. Now it's just seeing if they can upgrade the rotation with Beli, Metu and possibly a pick. Ideally, they move Mills for a forward making similar money (James Johnson from Miami, for example) and get the flexibility they need. Then they break up Murray and White and get a more ideal rotation:
Murray (some I won't get predictable backlash), White
Forbes, Walker
DeRozan, Carroll
Johnson, Gay
Aldridge, Poeltl
If Johnson can get back to his previous level of play, that's a dangerous team. He makes way too much, but at least he can't renege.