There is track speed fast, then there is on the field fast. Jerry Rice didn't wow at the Combine, but he wowed on the field with his speed. I wouldn't put too much stock on track speed in terms of baseball, unless Vogs is able to be as fast on the field.
But Rice wasn't exactly slow, top end speed is usually something you either have or don't. You might be able to shave a few tenths of a second off of a 40/60/100 if you are in decent shape and a second or so if you are totally out of shape by training. Other than that you are either blessed with fast twitch muscles or you aren't.
You can shave a lot more then a few tenths by getting into shape. Well, it depends what you mean by geting into shape, if you are going from top end high school talent to a professional athlete, it will probably just be a few tenths of a second. If you lose 40 pounds while gaining muscle mass at the same time, you'll probably drop a lot. Now, I don't know if Vogelbach really did get in a lot better shape, but if he did, he'd probably be significantly faster.
Pretty sure we are talking about the same thing.
If you run say a 4.7/40 in high school, you aren't going to run a 4 flat no matter how much you work, you have to already be in good condition to run a 4.7.
Now if you run a 7 flat because you sat on the couch and watched people run in high school and then decided to join the Army and actually had to get into shape there's a good chance that you might be able to run a 6 flat or sub 6 after you got into shape and actually developed some of the muscles required to run well.