He hasn't been the same since his hip surgery. It ended his 2014 season, and since then he has a 95 wRC+ in 567 regular season PA and 66 wRC+ in 46 playoff PA and his K-rate has increased dramatically while his power has been sapped.
Colorado doesn't trade Tulo for the return they got if they think he's healthy, normal, productive Tulo going forward. Maybe he'll rebound, but that's over 600 PA of pretty bad performance directly after a pretty serious surgery.