Some things Coaches look for:
Coaches want to see a pitcher’s average velocity- what your fastball is at on a consistent basis throughout a game. Your top velocityis also something they look at. Along with radar gun readings, they’ll look at movement, sinks,cuts,etc.
They will note at what arm angle you throw from. This determines how much tension, or effort, is in the arm action. A max-effort pitcheris tough on his arm and risks injury, as opposed to someone who is smooth and effortless. Pure arm speed is also noted, which usually translates to tighter rotation and better velocity .A pitcher’s arm action will also determine what type of break a curve or slider will have (down break, sweeping, sharp, loose, hanging, etc).
Are pitching mechanics clean and smooth, or is there work to be done with the mechanics? There are a wide variety of mechanical flaws that may prohibit a pitcher from being efficient and consistent.
While throwing the change, the pitcher must try to maintain his fastball arm speed, delivery, and follow-through. Quality arm speed and a good follow-through increase deception. Location is crucial. A change-up that creates deception, changes planes, and is thrown to the proper location is a wonderful pitch at any level. A good change-up is usually 10 to 12 miles per hour slower than the pitcher’s fastball. The change-up is a great pitch in itself, but it also enhances the fastball, making it appear quicker than it really is.
This includes curves, sliders, cutters, etc. College pitcher’s need at least one quality breaking ball to keep hitters off-balance. Good breaking balls have velocity, and they break late, have a tight rotation (tougher to read the spin), and hitters struggle to make solid contact with them.
Does the pitcher go after hitters with his fastball? Does he challenge hitters with his best stuff? Does he work quickly on the mound between pitches? Does he intimidate hitters with his body language and attitude?
Does he have a feel for pitching (knowing when to use his fastball or when to go off-speed); Is there field awareness for where base runners are and where the play needs to be made; does he back-up bases and cover first base when necessary; and does he support his teammates after an error is made?
Can the pitcher pitch, or does he just throw in the direction of the plate? Can he locate his fastball for a strike when behind in the count? Does he pitch ahead-in-the-count,or behind?
Coaches will evaluate a pitcher’s body to determine if he “feels” the pitcher can improve his velocity in the future with added strength training and using their College throwing program. They take into consideration a Pitcher’s current height and weight and if they are done growing or not. There are some 20 year old pitchers who have been weight lifting for 3 or 4 years and are so physically developed that it is difficult to project any velocity improvement from maturation. But on the otherhand, high school pitchers weighing 165-175 lbs. Adding 2-5 mph on their fastball as they gain weight and strength over the years in College is entirely possible. The problem is, strength and maturity does not insure added velocity, so this is purely projecting.
Since you’re a lefty you also will need to be able to get lefthanded hitters out on a regular basis.
Chances are you’d start out in the bullpen if you made the team so you’ll have to be effective every time you step on the mound. This is where mental toughness comes into play if you have a bad outing you have to be able to shake it off and be ready the next day or next batter.
Hope this helps you out