You just quoted top speed for an entire year. That's pretty definitive.
It really isn't. For example, was he coming off an injury, what kind of training was he doing at Stoke, was speed work optimal, was he constantly fatigued from training, etc.
I wouldn't say definitely that Shaqiri "doesn't have speed". I think that's fallacious. He might not be as fast as Mane or Salah, but he's not far off. But that's also beside the point, I think. He doesn't have to be as fast as them. He has to be faster than the opposition defenders, and I don't think that's something we can doubt.
I also quoted it to show that "MPH" is not really a great way to judge speed in football. We had your example which showed a lower MPH, and my example which showed a higher one, so there can be a lot of variance with that measurement I think. Unless we can see his yards per second numbers or its variations, we won't really know HOW fast he is, in football terms.
Acceleration is speed. He has acceleration, therefore he has speed. Has he got speed over distance? I'm certainly not sure, but I've seen him sprint over 50 yards, and he's not been caught while doing it. Does he have speed repeatability? That's the million dollar question, but if he doesn't, it's certainly easy to train (although as I think you pointed out before - it's subject to genetic limitations).