Aviles has a career UZR/150 at SS of 12.4. That's better than any other position for Aviles. In comparison, Scutaro's career UZR/150 at SS is 2.8. Aviles also has a better career wRC+ than Scutaro. Maybe this is what the Sox FO saw when they traded away Scutaro, they thought Aviles was better at SS, and they could sign a pitcher. I would still rather have Scutaro, because I still think he's a little better than Aviles, but hopefully, Aviles is as good or better.