Kronwall has had a TON of nhl success. Backman might have better "stats" because he recieved more quality ice time then Kronwall. Kronwall gets very limited ice time.
In 20 games, kronwall played on the 3rd pairing, little PP time, and recieved 5 pts, and a +5 rating, also getting 13:51 on average in ice time.
Backman has 2 times exactly more games played, 12 pts, and averages 17:07 in ice time, which is little more then 3 minutes more per game, which is a difference maker, and i assume with al and barrett out, he plays the pp unit, since he has only 2 pp assists on that, but im sure he gets more pp time then kronwall. You can argue that kronwall playing as a 4th dman, getting more time, 3 more minutes, and playing 20 more games, i could tell you that he'd have simular stats or maybe better stats then backman, since he was finally comming into a zone, only took him a few games or so.