Very much agree with Alarcon's sentiment that it's the influence of the coach that will change Messi's performances.
The way Messi is now, he's the judge and boss of his own actions. If he's our best player and doing his job of scoring goals (even that has dropped), then he's destined to give himself some slack. People can't always objectively command themselves to consistently work hard and do every single facet of their job (even the ones they deem insignificant to their ability, which to Messi is workrate and movement). If he is his own judge, then he'll cut corners and start slacking. If a coach is overseeing him with authority, then we'll see an improvement.
Not pleased at all with Messi recently but I'm not going to pretend that he suddenly just doesn't give a fuck. It's a human tendency, one that he has a pretty bad habit of.