I don't buy it, Lee showed some great form against New Zealand and then went back to his worst against quality opposition the next series (SAF). I think Lee and Johnson have a similar chance of swinging it really - only when conditions are right and luck is going their way.
Lee has a better chance of swinging it because his action is a lot more settled compared to Johnson. His wrist position is a lot better. As for his inconsistent form, he had a poor summer but the season before he showed his consistency including 24 wickets in 4 matches at 22 during India's tour of Aus in 07/08 a quality opposition. All you can go on is current form, and he was the best bowler in the tour matches so deserved a chance to show what he could do.