It is exciting that we have a regular season of baseball this year. (It is also exciting that the Phillies are currently sitting on a 3-0 win-loss mark.). It seems like a good opportunity to highlight some changes to the Baseball Savant website, mention updates to the baseballr package, and provide some current statistics on home run hitting in 2012.
I have enjoyed watching games this weekend using the Mlb.tv site. In addition to watching live baseball, Baseball Savant makes available live Statcast data for the game you are watching. For example, for every ball put in play, you can see immediately the exit velocity, launch angle, outcome, and expected BA. For example, you can see on Savant’s Game Feed that Shohei Ohtani’s 1st inning home run was hit at 115.2 mph at an angle of 21 degrees for a distance of 451 feet. There is much more live data on pitches and other things posted on this site. I guess one will now need two devices — one to watch the game and another to see the Statcast stats on Baseball Savant.
The baseballr Package
The Statcast data that we are seeing on Baseball Savant is available the next morning for download. Bill Petti has made some adjustments to his scaping function in his baseballr package so I encourage you to download the newest version of the package. What I currently do is download a day of Statcast data and combine it as a csv file with the data already collected. There are several new variables available. One has, for example, spin_axis and delta_home_win_exp — I believe the latter variable is the change in win probability for the home team on the basis of that play.
Home Run Hitting
As many of you know, Major League Baseball has said that there have been changes to the composition of the baseball this season with one goal to limit the home run production in the 2021 season. We don’t have much data yet — only data for four days of baseball — but I thought it would be interesting to look at the current rate compared to the in-play home run monthly rates for the last four seasons. Currently, we have seen 101 home runs in 2246 balls in play for a home run rate of 4.50 %. We see that this is the same as the April 2017 rate but significantly lower than the record-setting 2019 April home run rate. We’ll get a better idea if home run production has indeed decreased by the end of the month. As I have mentioned in previous posts, there are many factors in home run production including the composition of the baseball, the behavior of the players, and the weather.