Improving Command on Nonthrowing Days

Mechanics, mechanics, mechanics. When pitchers are able to repeat their motion to T every time they throw, it makes your control much better. A simple drill you can do is the towel drill (http://bit.ly/bCbDFv yes it increases velocity but helps with mechanics as well). When you say he has days where he scheduled not to throw I am assuming you mean off a mound or in a game? Pitchers can and should throw ALMOST everyday. Even the day after a start, many pitchers will throw just a light flat ground. If he has any kind of mechanical flaws, which almost all pitchers do to some degree, you should work on drills to fix them. If you aren't sure what he should be doing let me know what his flaws might be and I can help you from there. Was this helpful at all?

I'll second the towel drill as a means of working on specific mechanical elements that aid control. Specific things to work on include:

(1) Postural stability - Have him find a posture or starting position that he has the strength to maintain through his delivery. Strive to cut out all head movement side-to-side, back towards 2B, up and significantly down (downward movement is natural over the course of the stride - you just don't want a big drop right at the beginning of the stride).

(2) Glove-side control - Have him control his glove so that it doesn't fly open, drop or pull back as these things can affect posture and/or timing of shoulder rotation (i.e. premature rotation) which, in turn, will move the release point around.

RRF8- Very much agree with danramosd and Roger Thomas. There are a multitude of drills that can be performed that will break down the individual mechanics of a delivery, allowing a pitcher to work to control each part. Release point, foot plant, stack etc. etc. Tom House actually has some excellant stuff, although not everyone will agree. I might suggest looking at his material. I use a variety of material, some of which is specifically designed to help perfect mechanics, which will in turn improve command.
http://www.nationalpitching.net/

Great thoughts from everyone.

Beside these thoughts, I would really challenge him by observing all his throwing sessions to make sure he is getting the most out of it. This includes a bullpen, or even just a flat ground throwing session.

Make sure that when he does have the opportunity to throw, that he is using it as a target practice session. We only get so many throws as pitchers, so we need to make the best of them.

Stu