It's dry and this Dukes ball was brought in specifically to move about, it's got an exaggerated pronounced seam which tend to grip in dry pitches or pitches with a bit of grass on them. So it's nipping about, yesterday it swung and seamed, today it's really just seamed.
For all I rag on Australia's batting line up, yesterday you'd expect to get skittled for a low score. 250 ish would have been a good score, what they got was well beneath that but it was terribly tricky. Today it's really been a bit of seam of movement combined with some absolutely moronic batting. I mean as well as Australia bowled, only really Root got a great ball to get him out, pretty much everyone else just didn't account for the movement and played ridiculous shots. Australia have continued that with both Harris and Khawaja giving their wickets away.