I think the increased use of neutral rackers in the late rounds of all the majors is a factor worthy of consideration. In major tournament play, rack your own is on the endangered list.
Also relevant is the increased use of alternate break in major tournament play. More than any player of the last fifteen years, Shane has relied on stringing together packages, and thereby getting opponents frustrated and out of stroke.
Finally, the frequent use of the three-point rule hasn't helped Shane in recent years, as having to cut break in nine-ball, as so many players do when the three-point rule is in effect, to ensure compliance, hasn't helped his cause. At the International 9-ball, in the semis against Albin Ouschan, Shane really struggled with his break, and it cost him. On the bright side, Matchroom has announced the intent to do away with the three-point rule, and this will help him.
Shane, still one of the elite players, does best with rack your own, winner breaks and no three-point rule, but these days, he only seems able to get all three in gambling matches, and insists on them during pre-match negotiations.
I'm no expert on carbon fiber, but my sense of things is that Shane's major title drought of recent years has little to do with his switch to carbon fiber.