I'd say he was consistent last season - he made La Liga's team of the year ahead of Varane, Godin, Pique, Ramos and Pepe - and his performances domestically and in Europe were lauded. I watched a fair few Malaga games and they always looked solid defensively until after the Dortmund loss when their season seemed to end prematurely and they lost form/ran out of steam. His lack of pace could be an issue but as the video of him against Real Madrid shows, his positioning is very good so he is often in positions already. His performance against Dortmund in the 0-0 draw leg was out of this world. He made 18 clearances that day and was MotM.
Pellegrini has the Midas touch with these older players who seem past it. If Maicon was just joining us now and stayed fit, he'd probably have a good season under Pellegrini.