Ever wonder how to evaluate a Major League fastball? In this post we’ll look at the process of evaluating to types of fastballs: a fourseam and a sinker. We are only focused on the Major League level for now, as we would focus on different aspects of evaluating the pitch if we were looking at prospects, especially younger players.
If you prefer video breakdowns, check this out:
When we look at any pitch, we are focused on three main components:
- Shape
- Velocity
- Results vs both hands
Evaluation of a fastball can typically be done independent of the rest of the pitcher’s arsenal. But if we were evaluating a secondary pitch (curveball, changeup, slider etc.), we would also consider how those pitches play off the fastball.
Evaluating a Fourseam Fastball
Shape
When we are watching a fourseam fastball, the primary movement characteristic we are looking for is ride, which refers to vertical movement in the north direction.
Where can you find movement information? On Baseball Savant, you can view how many inches of ride a pitcher gets compared to the average of similar fourseams. Per the Baseball Savant leaderboard, Kutter Crawford and Matt Brash both get more vertical ride than similar MLB fourseams at their respective velocities compared to average. You can also use Brooks Baseball to get raw movement numbers (instead of ride vs average).
Spin Rate and Efficiency
When we are looking at movement, we also want to consider spin and spin efficiency. For fourseams, ideally the spin rate and efficiency will be high. For more information on what spin efficiency is, check out this article. Gerrit Cole, for example, has a plus fourseam. It has a spin rate of 2,430rpm and a spin efficiency of 98%. That means 98% of the raw spin is contributing to the movement, in this case the ride.
Velocity
The harder the pitch is thrown the better. Average fourseam velocity is about 93-mph.
We often see pitches that are thrown harder have less movement. The best pitches are the ones that are thrown hard and still get good movement. Spencer Strider, for example, has an elite fourseam because it gets above average ride, and is thrown 97-mph on average.
Control and Command
When we talk about control, we are talking about the pitcher’s ability to throw the pitch in-zone. A quick way to evaluate a pitcher’s control of a particular pitch is to look at the pitch’s zone rate. Pitcher List provides this information separated by pitch.
For example, Gerrit Cole has a zone rate of 50% on his fourseam, which is 1% better than average. I would consider Cole to have average control of his fourseam based on how close the zone rate is to average, and given he had a similar zone rate last season.
Be careful if you look at zone rate for other pitch types. For example, sometimes pitchers intentionally throw curveballs low/out of zone to get swing and miss. So the zone rate might not be the best indicator of their control of the pitch.
When we talk about command, we are talking about the pitcher’s ability to throw the pitch to certain spots of the zone based on where the catcher is calling it. There is not a stat that measures command, but we can get a good feel for it by watching games and looking at heat maps. If a pitcher is consistently hitting a spot and it looks like he is trying to get the pitch there, he has good command.
Below we are looking at Hayden Wesneski’s fourseam heat map. Based on my experience watching Wesneski and how concentrated the red dot is, I would say Wesneski has above average command of the pitch.
Results
It’s also very important to note how the pitch performs against both hands. Typically fourseams will work against both hands because they are moving north, which is a neutral direction for pitches.
Here are some results to look at using pitch specific breakdowns on Pitcher List:
- Zone Contact Rate: How often does a batter swing and miss against the pitch when it is thrown in-zone? Ideally, a pitcher will have a low zone contact rate on a fourseam.
- Chase Rate: How often do batters chase the pitch out of zone? The higher chase rate the better.
- xSLG: How much damage does the pitch cause? Ideally, xSLG will be low.
Evaluating a Sinker (Twoseam) Fastball
Shape
When we are watching a sinker, the primary movement characteristic we are looking for is sink, which refers to vertical movement in the south direction. Sinkers also have the tendency to run, which is movement in the armside direction.
Spin and Seam Shifted Wake
Similar to fourseams, the higher the spin rate and spin efficiency the better. But for sinkers, we also can look for another quality: Seam Shifted Wake.
At a high level, seam shifted wake describes the effect that seams have on pitch movement. It creates a movement profile that varies by the time it crosses the plate, making the pitch extra deceptive. For more information on what seam shifted wake is and how to identify it using Baseball Savant, check out this article.
Velocity, Command, and Control
The information provided under the fourseam fastball section above is also applicable to the sinker.
Results
In addition to zone contact rate, chase, and xSLG, we are also going to look at Ground Ball Rate for sinkers.
Because of their sinking qualities, we often see sinkers thrown to the lower half of the zone and they typically are a ground-ball inducing pitch. The higher the ground ball rate, the better, because that means the pitcher is likely getting weak contact off the pitch.
If the pitcher gets a lot of ground balls on the sinker, it’s okay if the zone contact rate is not that great. Ideally you would have a pitch that gets a lot of ground balls and in-zone miss, but the zone contact rate will often be worse for ground ball pitchers because they are intentionally trying to get weak contact from this pitch.
Unlike the fourseam, which is often neutral to both hands, sinkers are typically thrown to the same hand because of their running quality. When thrown to the opposite hand, the run mimics the bat path and can allow hitters to do damage. That being said, there are always exceptions. Pitchers with elite sinkers can get away with throwing them to both hands. I would consider a sinker elite if it was thrown at a high velocity with plus movement.
Watching Live or on TV
If you prefer or want to try evaluating in person here are some things to look for:
- How often are batters swinging and missing the fastball in-zone?
- How hard is the pitch thrown at the start of the outing vs at the end of the outing? If there is a huge drop-off in velocity (3mph or more), this is worth noting. Being able to maintain velocity is a must for starting pitchers.
- What kind of contact is resulting from the pitch?
Just remember not to set a firm opinion based on one look. This is where stats can come in and help us separate one-off notes from trends.