I am currently throwing a cutter (no arm pronation) that has nasty movement 7 out of 10 times. Does anyone have any suggestions on a new cutter grip? I use this: http://www.thecompletepitcher.com/how_to_throw_cutter.htm
Try an off center 4 seam with thumb under ball
How To Throw A Cutter … Like Mariano Rivera
To start, you hold it like a fastball. The cutter grip is a little bit off of center. Throwing it is like a fastball, and right here at about the release point, turn over your wrist.
The idea is, it’s got fastball rotation, and at about 59 feet, it cuts into a righthander for a lefthanded pitcher. For a righthanded pitcher it cuts into a lefthander.
I also recommend an off center four seam grip. For a righty, the seam should be shaped like a backward ‘C’. Put the middle finger on the curve of the seam with the index finger right next to it.
The key to a cutter is all in the release. It most be thrown with fastball arm speed and the action is applied by “popping the fingers down” to the outside of the baseball. Think about your fingers pointing down toward your left foot (instead of straight down the middle) to put the slightly off center spin.
Keep in mind, the cutter should have almost no downward movement. The key is that is looks like a fastball and at the last minute cuts laterally toward glove side.