I was watching a review of the Australia's summer and they mentioned about what a difference having a bowler who bowls at 150km makes.
It got me thinking that this summer Morkel was bowling about the same speed as Johnson, at worse averaging a couple of km slower yet Johnson took 22 @ 17.36 Morkel 6 @ 63.50.
The big difference in my opinion between Morkel and Johnson is Johnsons left arm slinging action. I would argue the issue batsman are having with Johnson is picking up Johnson action.
Are we making too big a deal of Johnson speed?