I think Paine's captaincy was atrocious after the 9th wicket fell. It was clear what Stokes' strike hogging tactic was. For about 6 or 7 overs in a row, he took a single off the 5th ball and let Leach face one. Surely at some point, this dawned on the Aussies and they could've brought the field up for the 5th ball and prevent him from taking the single.
Yes, that would've meant giving Stokes practically free boundaries for the 5th and 6th ball, but when 50 was required it was worth biting the bullet to be able to get a whole over at Leach. Even if Stokes would've been able to get the singles with the field up, as he did once, it would've been extremely hard for him to do this consistently. It may have encouraged Stokes to take the single on the 4th ball instead, thereby giving the Aussies 2 balls rather than 1 against Leach.
Either way, doing this would've given the Aussies a lot more deliveries vs Leach therefore increasing their chances of winning a lot more.
This is not just my opinion either, all the commentators were baffled as to why Paine was not doing this and Nasser Hussain even wrote about this in an article for the Mail. This was very poor captaincy and one of the many reasons Australia threw this match.