Magic get an elite rim protector and rebounder to anchor their defense in Jarrett Allen.
Cavs get a center who fits better alongside Mobley, because Wendell can space the floor and isn't a great shot blocker, but can switch onto most players and hold his own, while Mobley then takes the rim protection duties. This instead of having 2 starters with no offensive game and similar defensive games, thus handicapping the team.