Since Carr is going to get eaten up by good scorers, it's fairly important to rotate him away from such players in your man defense. So if this were my team, I'd use that as the primary test for where to play Oceguera or Carr. If it's close in that regard (opposing SG/SF are somewhat similar in scoring ability and proportion), I'd use Carr at SG and Oceguera at SF, since O's ATH, LP advantages and especially his PE, BH, PA disadvantages are much better suited there.
Edit: After looking more closely at the roster, Carr has to be at PG, with his SPD, and especially his BH/PA, which are far superior to anyone else on the team. Trent's the SG, and big O at SF, since O has the ATH and LP advantages, along with significant issues at BH/A to play SG, and fortunately, Trent is solid in both. IMO, his REB advantage is not nearly important enough to outweigh this. But I might switch them if you play an opponent with a dominant scorer at SG, one he goes to a lot, especially if the scorer is not way faster than 65. Then I'd put O on him and move Trent back to SF. Your scoring will suffer a bit, but not so much as to outweigh the advantage of trying to frustrate an important part of the opponent's offense.
At SF, I'd play big O at 0 or maybe even -1 against teams with low ATH/SPD SG and poor SB down low. With his ATH and passable BH (not good enough to create his own shot, but good enough to catch on the run and get to the rim, where his ATH can dominate even good defenders in D2), Carr can hit him for slashing buckets with his great PA. Good luck with him. He's a cool player.