Why do you think there is a day and night difference in Gambhir as a T20 coach and him being coach in other two formats?

I also noticed he is a lot calmer and smiles in t20 series,Is it because he has this freedom to take decision without the "big names" around, or is it because be is simply best suited for t20s and not made for other two formats, if yes do you recommend India try out different coach in other two formats?