Sounds like they have a couple months of official data, and a year plus of unofficial data. They should be able to compare actual check swing calls made by umps on the field with bat speed/location data and correlate those to come up with the magic speed. They also have to decide on the correct location to measure the speed... the tip of the point of the plate? The center of the plate? The front of the plate?

IMO - check swing rulings as currently implemented are as big an issue as ball/strike calls. They change at bats based on highly subjective rulings. I also don't like a fact that the defense can request a ruling from the 1st/3rd ump, but the offense can't appeal a ruling to the 1st/3rd ump. The field umps can overrule a "no he didn't" call by the home plate ump, but they aren't able to overrule a "yes he did" call.