Guardians Of The Galaxy managed not only to pull of the feat of getting audiences to care about a comic book team they had never heard of, but they also managed to make audiences care mostly about the two non-humanoid members of the team: Bradley Cooper as the diminutive Rocket Raccoon, and the Vin Diesel-voiced tree-person Groot. A combination of special effects and actual voice talent (albeit with Diesel only saying the word "groot" in various different intonations) is what made them work so well. It was probably a lot less enrapturing on the set when the ten-foot-tall tree-person was represented by a tall man in a morphsuit wearing a Groot head as a hat. No wonder Chris Pratt looks so bored.