"According to a source, incorrect information was reportedly conveyed to the team, which led to a mistake..."
"The NHRA tech department made a mathematical error in weighing the car...,"
I read the article a few times to make sure I read it right. It doesn't sound like just a simple under weight issue, it was cause and effect.
I'm sure this was just a simple mess up and have no inside info but I can imagine it playing out as simple as this.
Mike wins a round and gets held for an interview on top end. I'm sure in the quick turn around times last weekend, if that happened, they will for sure send the car back to the pits without the driver. I think NHRA has a chart of drivers weights for this type of scenario. So they weigh the car, and look up Mike's info and add them together. Minimum weight is 2340. To keep things simple, lets say NHRA tech says mistakenly the overall weight is 2360. So it's 20 over. Since they are 20 over, the crew takes 10 pounds out to leave some room for error. Lets say the weight was actually 2345, not 2360. Now with the 10 pounds out, and the math done correctly next time they come across the scales, they come up with 2335 which is under.
OR- Another hypothetical, I'm pretty sure some tracks have scales that are not long enough for a fuel dragster. So they measure with the back wheels on, then the front wheels on, and come up with the overall weight. Same thing applies with the above scenario from there.
I could be totally out in left field, but it's the only 2 examples I could think of where somebody would need to do any kind of mathematics to come up with the weight, not just roll the car on, have the driver stand with the car on the scale, and you get the number.