Yeah, Alcock was running across field to cover Shipperley. Shipperley had no-one outside of him, and stepped back on the inside of Horne, who was wrong footed and didn't even lay a hand on him. Alcock slipped the tackle, but he was Horne's man all along. Horne has had a habit of setting himself on his heels too early, allowing him to be cleanly stepped.
edit: gotta be Horne's man, surely. Horne should've moved up with Alcock, but remained too flat footed and allowed him to be stepped. That said, Alcock does bear some blame too.
edit2: gees, Horne was lazy on that last play. But really, the Reds shouldn't have won that. If it wasn't the first round of the year, you'd think that Tahs would've never have screwed up so badly in giving the ball back, and not chasing the kick.