Napao's top control looks shaky mainly because he's almost constantly looking to do something else, whether it be advancing position, throwing strikes or slapping on a submission. A more steady approach would probably benefit him against Filipovic, but Napao has as wide a selection of submissions as anyone at HW (even if he can't finish that arm-triangle to save his life), and stands a good chance of catching Mirko in transition on the mat.
However, despite having something of a good style to match-up with Mirko, he's still a bit too raw for the fight at this point.