Ah. Don't worry about it. Happy to try to help. Glove radar does pick up and "across the plate" speed. It uses a rather week Doppler system to read speeds from about three feet away. The ball is naturally going to slow down after it leaves the pitcher's hand. There's no longer force being applied to it. Like shooting an elk deer with a 3006. The further away, the more drop in the bullet since force is being slowly lost over the course of distance traveled. A baseball slows some 1 mph per 7 feet traveled. You have to subtract or add to get the out of hand speed.
Now, as to the two seamer matter. What's the difference in shooting a 3006 vs a 38 snub? Obviously the load, but as you probably know, barrel length is a key factor. But even more than that is riffeling. 38s have shorter barrels and less riffeling as a result. Bullets lose speed pretty quickly and begin to drop. Now, what if you have a civil war era muzzle loader and a 3006? Barrel lengths can be similar. The muzzle loader probably even longer. But, those old muzzle load guns had no riffeling. This no spin and shorter shot length and decreased accuracy. Same applies with baseballs. The more back spin a pitcher puts on the ball Nd the more seams that are cutting through the air, the faster and straighter the ball goes. The aerodynamics will also cause it to drop less. Two seamer have fewer seams cutting through the air. You have more drag on the ball, and while the ball may even spin at the same rate, aerodynamic principles will say that the ball HAS to drop more and will go slower. Just like a mussle ball or 38 snub shot.