He's played more than one series in his career.
You probably wouldn't have seen it, but Michael Clarke's fielding in his debut test series (against India in '04) was absolutely horrible, at least in terms of catching. He put a number down fielding in a few different positions, and sitters as well as tough ones. He's obviously a world class fielder though, it was just an aberration (unless you're Richard, who thinks he's crap), and there's not too many guys in the point area who are better at stopping the ball, and probably nobody who is better at throwing down the stumps.
Pietersen's not the best fielder in the world or anything, but he's certainly very much above average. The best in the England side after Collingwood, at least in terms of versatility.
Incidentally, the inclusion of McGrath is hilarious. One of the best fast bowlers ever in the field. He's not quite as good these days, but he's still by no means bad, and that's at 36 or so.