While I admired his tenacity and his desire to overcome his situation, the truth is, it is extremely difficult - if not impossible - to excel at the highest level of sports and athleticism, particularly in a game like football, and not be at peak performance with all of your faculties. The best athletes are rendered virtually useless by a severe injury to a body part - let alone not having a body part at all.
Something as small as a toe (turf toe injury) robbed Deion Sanders of his elite speed. And I suspect Jaylon Smith's devastating injury is why he hasn't turned out to be the elite player he was projected to be before his injury. I still think it's a mental hurdle he hasn't gotten over yet. You have to be super elite or athletically otherworldly (aka, Emmitt Smith and Lawrence Taylor) to play at a high level with major injuries (that and a shot of Novocaine to deaden the pain).
Anyone who runs/ran track can tell you that you need your hands working in conjunction with your legs to reach maximum speed. Your hands act as pistons and as rudders to speed you up and slow you down.
The physical demands of a game like football require peak physical performance, which is why most of us aren't professional athletes, why women outside of kickers and punters aren't suited to play in the NFL (not sexism but science) and why Shaquem Griffin will have a hard time being a starter in the NFL.
I'm not going to make fun of him because, again, I applaud him taking his dream as far as it would take him, and I would encourage anyone who thinks he/she can to go for it. But, realistically, it has been and is going to be difficult for him to be anything more than a special teams player because of the absence of his hand. And with defenses becoming more limited in how they can tackle offensive players, you need all the advantages you can get.
Sorry, if this offended anyone. I didn't mean to. But I wanted to get to the heart of the matter - as I see it.