Michael’s shaky 2014 season was due mostly to missing most of the season with a shoulder injury and not having a quality third pitch. His fastball\changeup combo is one of the best in the league and he has developed a pretty decent curve over the winter (as referenced above). Wacha already throws pretty hard (mid 90’s) and having that 6’6" frame gives him the added benefit of a higher perceived velocity. His height and high arm slot gives him great downward angle on all his pitches making things even more difficult for batters to hit him. I know this doesn’t really answer your question as to “how” he throws so hard. I just like to brag on one of my favorite players. Got a picture of him standing next to my wife when he was down in Springfield (AA Cardinals). She’s about 5’4. It was difficult getting both their faces in the frame to say the least.