Becoming a Data Driven Program- Part 1: In-Game Data

Jonathan Gelnar
Sep 16 · 9 min read

Link to audio version-

Earlier this month I wrote about some of the things we are changing from last year to this year. A big part of that is how we are incorporating technology. Let me start by saying that it is not easy and it never goes as smoothly as you plan!

When I took the job at Union I knew we would have some great resources and facilities to use so I wanted to jump all in on being data driven. Little did I know that the same day that I was hired, they also hired a data collection agent. Yep, that was me too. When it comes to data and tracking, I am that person. I will be the first to admit that the following is not a perfect process. It will be one that will be refined many times, but here are a few tips on how to make it more efficient and save you countless hours of time.

Step 1

Start with the scoreboard and work backwards. How will it affect the bottom line or the end goal? Collecting data shouldn't start with what we can gather but begin with what you want to achieve. Then look for the data that will impact that.

— Fergus Connolly

Before you start, there are a few important questions you need to ask yourself and your coaching staff.

  • What is important to us?
  • Does it transfer to the game?
  • How can we communicate this effectively to each player?

It is one thing just to collect data and another completely to use it to help our players get better. I’m the first to admit that collecting data can be a monumental task, but if it is important to us, then having objective feedback and a system for collecting it is vital. We also need to understand that if it doesn't transfer to the game, it doesn't matter.

Lastly, if we cant communicate it to the player in a simple and concise manner, we don’t understand the data well enough. We have to know what we are looking for, we have to understand why it’s important, and we have to know the player to communicate effectively. The last thing we want is to have our players confused by what we say or for us to change our mind several times on what we’re interpreting. If we can’t do this, the best outcome is that we are just using it for evaluation and not player development and the worst outcome is we make our players worse. So here are a few things we are looking at to try and get a picture of how we can help our players.

What we are tracking.

Flightscope in game data from last season reports.

Thanks to BaseballCloud all of our in-season reports were posted on a 1 page report based on several metrics we asked for.

  • Exit velo per pitch (location and pitch type)
  • Launch per pitch
  • Spray charts
  • Hot zones

*Downfall — only about 15 games so not a huge sample size

How we are using it to correct issues?

When going over player reports, one of the first things I always ask is “what is something you feel you do well, and what is something that I can help you with this offseason?” This involves the player but it also shows me how aware they are about themselves. For me, in game data is king. It’s the ultimate test of understanding if what we are doing is working or not. It takes the opinion out of my hands, and the players hands and can give an objective look at things we do well and what we need to work on this offseason. Again, if it doesn’t help with transfer to the game, then it doesn't matter.

When looking at these reports there a few things that we need to consider. Number one, I want to know what the player is doing well. I know this sounds extremely obvious, but sometimes we get more hung up on what the player can’t do, than what the player can do. This is especially valuable in season when it is not the time to make major swing overhauls.

A great second step to this equation would be- Does the player even know that they do this well? It may not be as obvious to the player as it is to us. There has been countless examples of MLB players getting traded to teams who noticed these trends and turned the players career around. I have no insight to these instances but I want to do my best to communicate these things to the player, so they can be aware of their strengths and areas of improvement.

So how are we using each of these metrics?

Lets start with exit velo per pitch (location and pitch type)

Here’s a report from about one of our players. If you’ll notice, he hit fastballs fairly well and had an average launch within the range that we wanted from most of our hitters. For most, the goal is 10–15*. (To compare, Pete Alonso’s this year is 13.8*). But he struggled greatly with breaking balls and couldn’t keep them off the ground. For this particular player they landed right in front of the plate. I think this is fairly common with most high school hitters, but something we would want to avoid at all cost. This was a conversation we had with this player all year long, but data also backs up our observation.

So what are we doing about it?

We need to look at this holistically. For this player, is it an approach issue? Swing issue? Timing issue? Pitch recognition/adjustability issue? These are all coactives in the swing and at times we teach each of them independently. In the end, they all depend on each other.

This is another area where we need to involve the player and ask. We all can have theories, but it only helps to understand the players viewpoint as a starting point. If we solely use the data to tell the player whats wrong, I think we’re missing 3/4 of what is actually happening. I don’t think most players will be completely bought in to changes if we don’t look at this holistically and get their opinion. This particular player has a swing issue where he gets extended early, so when he is on time, he can hit the fastball really well. But this poses a problem when he isn't on time because he cant adjust his body, even if he recognizes the pitch early enough. This offseason, we’re working on starting in a better position in his setup and landing in a less locked out position when he lands on his forward move.

Here’s a report Launch per pitch type

This is one of our promising young players. Knowing the player, he has great hand-eye coordination and bat to ball skills. He’s also weighs around 130, so one of his goals this off season is to put on 15 LBs. Why does LA matter with this particular player? Well, we don’t want to be hitting the ball straight into the ground. If you’ll notice this player did, a lot. He hit a ton of balls that had several hops before getting to an infielder. Its also concerning that his curveball launch angle was negative. I know the goal is not to hit it on the ground and especially when it has to bounce several times before it gets to an infielder. Our goal for most is to hit line drives over the infielders and the average LA of 3.4 isn't close at all.

Again, we need to look at this holistically. Approach issue? Swing issue? Timing issue? Pitch recognition/adjustability issue?

With this player he had no trouble putting the ball in play, so we had the conversation of not swinging at pitchers pitches. He wasn't a threat to strikeout a lot but would get himself out and get jammed or roll over pitches that were off the plate. We also want to tick up his LA a little bit, to turn his hard ground balls into line drives and his choppers into ground balls that are trying to break the infielders shins. I wish I could trademark the last line, but that one is all Dan Heefner.

The last report we are going to look at today is hot/cold zones

This is probably my favorite one to look at. As I alluded to earlier, sometimes players have no idea what areas of the strike zone they hit hard and what they don’t. Being able to understand this is vital to being a productive hitter long term. Above is an example of one.

How are we using it?

In season- Do we know what we are hitting well? And how often are we swinging in that zone? Using both of these, we can setup BP rounds that curtail to that specific player and you get a point for each ball you swing at in those zones. Most coaches do these rounds in practice, but having data to back up specifically what your zones are is extremely beneficial.

Off-season- each player is going to have some cold zones. Even Mike Trout. (below)

But understanding what they are is half the battle. We can then narrow down what is causing the issue and work on it during practice. For this player this off season we will be working on not swinging at pitchers pitches. He can hit, and he will only get better when he lays off the up and in, and low and in pitches.

For in season, a simple chart with + or — for whatever is important to you. Such as, fastballs in the middle of the zone, + for swing, — for take. This runs into a few issues. One being, if we take a pitchers pitch on the black in a hitters count and it being counted against us as bad decision (it shouldn’t be a negative). But if it’s important to us, we have to give feedback to our players on when they make good and bad decisions at the plate. Driveline has a fantastic series on this.

If you don’t have the convenience of an analytics staff, come up with a simple system your players can fill out for you during games and keep track of these during the season. Training this on a daily basis can go a long ways in training better decision makers and for building more aggressive hitters.


I know that was a lot to go through and I know that a lot of our readers will not have the ability to track this information. The biggest thing I wanted to get across with this article was trying to simplify the endless metrics we can use to measure hitters. When your data collection team is a team of one, this can be daunting, so knowing what to look for with each player is a major key. I’ll go over some different devices we have used and our process for collection in the coming weeks.

In the end, we want each player to know themselves. To know their strengths and deficiencies. It’s our job as coaches to help our players understand this, but to also set up a practice environment that enhances their strengths while continuing to work on their deficiencies. The is the essence of true, individualized player development.

Have a great week!


Jonathan Gelnar

Written by

†follower. Husband. Influencer of our nation’s youth through the national past time. @union_baseball. Host of @aotc_podcast

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