This post isn't so much an answer to the question above, but a graphical comparison of how Mitchell Johnson - once so maligned, so fragile - and his fellow bowlers have stacked up over his six-Test run of supreme dominance.
Times past, the presence of a dominant bowler led to unnerved batsmen taking unwise risks against good quality flingers from the other end - it's a phenomenon noted as early as Bill Lawry's immortal tome, Run Digger when the fearsome pace and questionable action Charlie Griffith had the Australians touring the Windies in 1964-65 take risks against Wes Hall.
The alternate sees one bowler collecting on the fine work of a group - while still requiring much of the bowler, extra pressure exerted by his teammates plays on batsmen's minds and creates more wicket-taking opportunities. For examples of this, see the West Indian attacks of the 1980s and almost any Australian attack from 1993 to 2007.
This Australian attack isn't necessarily one to be feared (they had a bowling strength of 28.58 for the second innings at Centurion, a good-but-not-great score), but they do their job. It turns out they're really good at doing a job.