If you watch Spurs' 3rd goal yesterday, he's not cuaght out because he's involved in attacking play, he's caught out because he's shit. Jumps out of the line to attempt a tackle he can never make, doesn't bother tracking back, gets let off by a slow lofted pass which lets him get back in position, but he doesn't even try to stop the cross.
He is a poor defender. He's poor 1v1 and has big lapses of concentration. He's quite good as a proactive defender in midfield, often he has free reign to go for interceptions or tackle people as they receive the ball because they're not used to having a guy coming off the win into midfield, but that's not really defending, it's more midfield play.