Online vs. Live players

[Swedebubba]

I asked a derivative question of this awhile back in the General forum and got ruthlessly flamed so I'll see what you guys think.

Last month Cardplayer mag. interview Mike Matasow. In the interview he described online poker players as the worst kind of player skill wise.

So my question is, if he is correct why is it generally said that if a player can beat 3-6 online at a decent rate that he could play 15-30 or even 10-20 live with relative ease?