I worked with a guy that sparred with Floyd for two fights; subsequently he sparred with Canelo before the fight with Floyd. In those days it was easy to at least be competitive with Canelo; he needed time to set and punch. So you pop off- two punches and move- before he could punch back. He had that issue at least until the Cotto fight, and I have seen video of how frustrated he would get in sparring when trying to deal with guys that would punch to set him, then move.
He has improved dramatically over time, but he also likes to fight guys that don't move much. To be fair, everybody hates to fight movers. But, if you want to beat Canelo, it is in crisp punches, never more than 2, then move. Pop a jab, feint, slide over right hand, then move and hook. Break his rhythm by using feints and short slide steps.