Because McDonald is such a good batsman? Honestly, his presence in the side itself gives us a better shot of winning than without him.Can't see England bowling Australia out twice with Mcdonald at 8 and Johnson at 9. As long as the last two are Siddle and Clark I think they will have enough bowling as well. With Hauritz in the side I think they might struggle if they had Ronald as part of a 4 man attack as well.
I think that provided everyone is fit, our bowling attack will be the least of our worries.