Traditionally, rookies don't start in Pittsburgh, especially not on defense. That was about as close to a sacred rule as you could get.
Of course in 2013 a severe lack of depth and an untimely injury to Larry Foote pushed Williams, a 6th round draft pick, into major playing time. For Williams' part he played admirably given the situation, however for Jones' part, a 1st round pick, he may have been thrown in to the fire prematurely and expectations raised too high.
In any case, both players showcased why rookies don't start on the Steelers defense, because mistakes will happen.
So when the Steelers drafted another linebacker in the first round of this years draft, inside linebacker Ryan Shazier, many were curious as to how significant a role he would play. After all, Williams hardly locked down the spot opposite Timmons, but the dangers of starting a rookie were fresh in every ones mind.
After a solid effort in OTAs, with the occasional spectacular moment thrown in, it appears Shazier is headed toward a significant role in the defense, with perhaps even a starting role in contention.
Per Ray Fittipaldo of the Pittsburgh Post-Gazette, Steelers linebackers coach Keith Butler suggests that Shazier will absolutely see playing time on the Steelers defense as a rookie.