That is a really strange move. They seem to be very similar players, Carlos had a down year in 2018 but Encarnacion is older.
Basically trading a bit of OBP for a little extra pop.
Encarnacion is earning a little more (20M vs 17.5) and has a 5M buyout for the 2020 season while Santanas contract is guaranteed for 2020 but comes with a 500k buyout for 2021.
I honestly don't understand why either team makes this move. Neither gets much better or saves much money. I guess you can say Cleveland just really likes Carlos and is happy to have him back and Jerry Dipoto just likes making trades.