Sooooo.... Why now? Why wasn't he awesome before Manny got there?
Week 1 - got way ahead, stopped throwing
Week 2 - 5-86-1 (grabs attention)
Week 3 - 3-44, Jimmy G was a mess and this was Pittsburgh
Week 4 bye
Week 5 - got way ahead, stopped throwing
Week 6 - 3-18 + 1 rush attempt then injured
Week 7 - didn't play, injured
Week 8 - got way ahead, stopped throwing...but did net 3-19/2-29-1 in his first game back from injury
Week 9 -4-40 (7 targets though - attention getting grabbed again)
Week 10 - breakout post Manny injury, 8-112 (11 targets)
And in those last 3 games his snap count has increased to 70%, 66%, and 83% at the expense of Pettis, who dropped below 40% in each game. Before then he topped 60% just one time (week 1). Not all trends are linear, but you can see where this may be pointing. Plus, as Naut said - he's a rook. It's perfectly normal for one to have a bumpy start and an upward trend as the season progresses.