It appears the Tigs are involved in a 3 way trade, Avi Garcia goes to Chitown, Peavy goes to Boston, and Jose Iglasias comes to Detroit, per Danny Knobler on Twitter (among others). Iglacias can play SS, 2B, 3B and is hitting 330 in 200+ at bats in the Bigs. Locked in for a while, until 2019.
EDIT: appears Brayan Villarreal is also included, going to Boston
Side note - AP reports Biogenesis suspensions will be announced on Friday, Peralta to accept it.