With Bruce Arians leaving to take the head coaching position for the Arizona Cardinals the Colts have brought in Stanford offensive coordinator, Pep Hamilton, to fill the open OC spot. Obviously, Hamilton comes in bringing past experience running his own version of a West Coast style offense that he ran with Andrew Luck during his time at Stanford. While Hamilton's style is most certainly a very different philosophy from that of Arians, it will be a familiar one for Luck.
The signature offensive style of Bruce Arians tends to involve a focus on downfield passes and pass plays that typically require more time for routes to develop. The practical upside, obviously, is big plays. Indianapolis finished the 2012 season ranked 3rd in the NFL in passing plays of over 20 yards and 5th in passing plays of over 40 yards. The Colts were typically pass heavy in 2012, and this resulted from a combination of offensive approach and from limitations of the offensive line in run blocking. For the season they attempted 628 passes for 4,128 yards, tallied 23 passing touchdowns, and averaged 258 passing yards per game. On the flipside, the Colts rushed 440 times for 1,671 yards and 11 touchdowns with an average of 3.8 yards per carry. The split was just under a 60/40 between pass and run. This style has some boom or bust potential, and one significant downside is that it puts a great deal of pressure on the offensive line to hold blocks long enough for plays to develop in the passing game. Andrew Luck was hit the 2nd most times of all quarterbacks in 2012 (116 QB hits), and was sacked 41 times (#9 in NFL).
This pressure on the offensive line in the pass game and potential to give up sacks and QB hits is simply part of the Arians style. During his time with the Pittsburgh Steelers as offensive coordinator from 2007 to 2011 the team was in the top 10 in sacks allowed every year. That's not to say the philosophy is unsound, but it does have a certain personnel requirement with the offensive line. A team with a very strong O-Line that excels at pass protection could really make the Arians style shine. As we saw in 2012, the Colts did not have the offensive line to make the most of this scheme. Despite the great successes the team saw, Andrew Luck was one of the most terrorized quarterbacks in the league. He was under constant pressure behind an O-Line that couldn't give him the time needed in the passing game more often than not. Fortunately, savvy decision making and great athleticism on Luck's part kept them alive amidst these struggles all season.