There's a statistic named "Pitcher Abuse Points(PAP)," which is to measure how much starting pitchers are "abused."
Let xi be a number of pitches for each game.
For xi>=100, the statistic is calculated as follows.
PAP = Σ(xi-100)^3
You can see this year's ranking of PAP on the following link.
Justin Verlander ranks the top with a big lead on the others.
He also dominated the position in 2009 and 2010, which shows he is heavily relied on.
Yu Darvish comes in next to Verlander.
Considering he has less number of game started than others, he has high number of pitches for most start.