Using Batted Ball Data in Scouting

Editor’s Note: This piece was initially given as a presentation at the marvelous 2015 Saber Seminar.

Scouts have been trying to measure a hitter’s power for years. The best way they have found is to show up to the ballpark two to three hours early and catch batting practice. Then they judge how far the player can hit the ball and give the player a power rating from 20 to 80. This isn’t a foolproof plan, however. Sometimes you can’t get to the ballpark in time, sometimes there is no batting practice, or sometimes the player you want to see doesn’t take batting practice. Stuff happens, in other words. And even if you do get to see the player you want in BP, it is tough get readings on a player with just a few swings of the bat. Maybe the player isn’t as good as you thought, or maybe said player is working on something other than “hit the ball as hard as you can.” But, by using some batted ball information that has become available over the past few seasons, some new ways are potentially available to measure a hitter’s power.

Two available pieces of information are fly ball hang times and batted ball velocities. Inside Edge tracks fly ball hang times, but we have not found many ways to use that data until now. The batted ball velocity data, as you may know, is just becoming available to the public this season. I don’t feel the best about jumping to any conclusions with just part of a year’s worth of data, but some information is better than nothing. Analyzing both pieces of data will be a nice starting point for further discussion and research.

In attempting to use these tools to measure a prospect’s power potential, I used the power values provided by FanGraphs lead prospect analyst Kiley McDaniel—Game and Raw—for prospects who have been promoted to the majors this season. Additional information on his power ratings can be found in this article. I collected the prospect power values (and the rest of the data) on July 21, so the values will not line up with the player’s current stats. Again, I know this is not even close to being a perfect amount of data to draw any long-standing conclusions. But it is a starting point which can be refined as more data become available.

Hang Time

Until recently, I have never considered those towering infield fly balls to be useful for anything except to see how hard the hitter can slam his bat to the ground in frustration or the possible collision of a couple of non-communicating fielders (which is always funny). However, the amount of time a ball stays in the air can contain some useful information. By filtering only the outfield fly balls, here are the top players in average and max flyball time (minimum 600 plate appearances from 2012 to 2015):

Average Fly Ball Times

1. Chris Carter: 5.47 seconds
2. Adam Dunn: 5.39
3. Jason Bay: 5.38
4. Dan Uggla: 5.38
5. Giancarlo Stanton: 5.36

Maximum Fly Ball Times

1. Dayan Viciedo: 8.7
2. Mike Trout: 7.8
3. Justin Ruggiano: 7.8
4. (T) Mike Napoli, Alex Rodriguez, J.J. Hardy: 7.7

For an example, here is the 7.8 second Trout fly ball.

It takes a fairly decent power hitter to average over five seconds on his fly balls, or to even hit just one that spends more than seven seconds in the air.

Now, it is time to put some everyday stats behind the fly ball times.  Here are R-squared values for isolate power (ISO), home runs per fly ball (HR/FB) and homers per 600 plate appearances (HR/600 PA) compared to the two fly ball values (minimum 200 PA per season):

The R-squared values aren’t the greatest, but the there is definitely a slope to the data. I bucketed the hang times to get some average power values and put all the players’ average flyball values into a range. Additionally, I matched up the scout grades from Kiley’s scouting table based on the HR/600 PA values:

To have major league power, a hitter may need to be able to hit a fly ball with enough “oomph” to have it fly for six seconds or more.  Additionally, the hitter’s average fly ball times need to be at or over 4.5 seconds.

Now that we have some historical perspectives, it is time to line up the fly ball values with Kiley’s scouting power grades for this year’s rookie class. While I have four years’ worth of fly ball data, Kiley has been at FanGraphs for only one prospect ranking cycle. I took the rookies with at least 50 plate appearances and I ended up with 33 players. Not a ton of players, but here is how their current game and raw powers grades line up with the fly ball times:

While dealing with this small sample of prospects, there is a definite dividing line between 40 and 45 game power and 50 and 55 raw power. An average fly ball time of over 5.0 seconds puts the player into 20 home run territory (ie, (above average power). Also, a player who hits a single fly ball in the air over 6.5 seconds is likely to be in that same 20 home run range.

Looking over the players Kiley graded, a few don’t have scouting power scores that line up well with their 2015 results. The first is Carlos Correa. His game power is at 20, which is barely serviceable as a major league player. Correa has hit a fly ball at 7.1 seconds and is averaging 5.2 seconds on his fly balls. This would put his power in the 55-60 range, not in the Jarrod Dyson-like 20 power range. So far this season Correa has hit decently. He is on pace for 31 home runs, a .241 ISO and 22 percent HR/FB over a full season. The other players Kiley may have been a little conservative on are Joc Pederson and Steven Souza who both got a below average power grade of 45,  have average fly ball times of 5.3 and max fly ball times of 7.1. Each of those values indicate above average power.

To use these values for scouting, I would concentrate on the maximum value range. Scouts are usually starting their stopwatches at the point of contact for a time-to-first measurement. A player is not sprinting to first base on a high towering fly ball, so the scout can let the stopwatch go until the ball eventually lands. Since, I started tracking these numbers on the amateur level early this summer, I have seen only one ex-major leaguer hit one over 6.2 seconds. The best top values have been generally in the 5.5-second range.

It is easy to time the ball from the moment of contact and get a good reading. For people who will see a player several times, a hitter’s average value can be tracked. It is far from a perfect method to determine a hitter’s power, but it is just one more possible data point to help with evaluation.

Batted Ball Velocity Data

The data the public has been waiting a few years for is now available: batted ball velocity. While I have seen the data tracked for hitters by scouting services, there has never really been a reference point for what is or isn’t a good value. Well, now some data can be collected and used. Here are the R-squared values comparing HR/600 PA, ISO and HR/FB to a player’s max velocity, average velocity and average fly ball/line drive velocity (minimum 50 plate appearances):

Not great R-squared values, but again, a slope does exist.

Let’s look at the actual values of the velocity information below. I bucketed these just like the fly ball times. One item that sticks out immediately is that only one hitter has a maximum velocity under 100 mph (Tyler Flowers). A key maximum exit velocity to begin to take notice on is anything over 108 mph — that is the league average. The average values create better results in that they smoothly change from one value to the next:

Note: Giancarlo Stanton is hella good. Now, here is how the batted ball velocity values line up with the ranked prospects.

The splits are obvious. A player with a maximum exit speed over 110 translates to having above average raw power (55 or more) or average or better game power (45 or more). The two average exit velocity values, total and FB/LD, are also broken up at the same 55/45 levels.

Now comes the problem for scouts: How can they use these major league values in parks without pitch speed detection cameras? In addition, as we have discussed, a perfect time to evaluate hitters is during practice, but the batted ball speed is always greater than the pitch speed. In batting practice, a hitter can really tee off on the incoming meatballs and add some batted ball velocity. One roadblock to this method is the batting practice pitch speed. Professor Alan Nathan has determined pitch speed has some effect on batted ball velocity. The effect is only a sixth that of the bat speed, but it is not negligible.

Another possible source is in showcase or prospect events. These events, such as this showcase put on by Prep Baseball Report, have started to track batted ball velocity. This isn’t foolproof — for instance, the hitters are usually hitting off a tee. And the measurements may not be as sophisticated as those in major league parks. But it’s a start.

As for which batted balls to track, I think the key value will be the maximum velocity. Unless a team is able to track its own values over several games or hitting practices, the values will probably be useless. I am wondering if a maximum batting practice value could be tracked for players. At this point, the scout is seeing the ball travel and giving the player a traditional power ranking by how far the ball travels. This method for tracking power can be done, but it takes a little more work and possibly a second radar gun (which isn’t optimal).

Conclusion

After going over some batted ball information, it seems like fly ball times and batted ball exit velocity may be a good way to help measure a player’s power. The results are not perfect, but with the limited amount of data available, I am surprised that the results worked out as well as they did. Overall, the average values give a better indication of the player’s true ability, but it would be hard to track. Instead, we could use the maximum values, or instances when a certain value is reached — like 6.0 seconds for a fly ball in the air or an exit velocity of 100 mph or more.

I have just begun putting this information together and I believe so much more can be learned. I think teams may have already been doing this work, as they have had the data for years and with larger budgets than FanGraphs. I think the key will be to go back and re-examine this information in about a year and half. At that point, two sets of batted ball data will be available for correlation and I (and others) can begin to put the preceding information through more rigorous tests. I look forward to checking some of my conclusions.

References & Resources

• Kiley McDaniel, FanGraphs, “Scouting Explained: The 20-80 Scouting Scale”
• Scouts with whom I have spoken.
• Inside Edge
• Baseball Savant
• Prepbaseballreport.com
• Alan Nathan, Baseball Analysts, “Comparing the Performance of Baseball Bats”