Comment by reedf1

    Participants were instructed to maintain their current 
    dietary habits and physical activity levels for the 
    duration of the study.

My understanding is that creatine increases the amount of available energy for muscles to use (hence increases sports performance, training performance, and recovery) - not increase muscle growth alone. That said - it is an interesting study which helps decompose the effect, this shows that creatine likely provides no other additional benefits.