Great analysis of the positives. The only things I would add about his positives are that he presents quite a challenge to the defense on slants, which this analysis did not really explore. Also, splitting him wide, whether via motion or not, opposite side from Stills presents many defenses with a huge choice. Either they back off the run and commit two safeties high, or they play one safety high but so deep it almost negates his effectiveness as anything other than a last line of defense, or they risk getting burned deep. This is the same dilemma they face when Grant is in the game with Stills.
While putting either of those two groupings sounds like a pass play, if there is another RB on the field with either of them, then it can also be a decent run solution. Putting Drake and Ajayi in the game together sounds strange, but that isn't a bad combo really if you are using Drake as an extra WR. This game is a game of matchups, and many defenses simply don't have an answer for two guys with that kind of speed other than to play off and give one of them an easy reception.
What this article does not address are the cons of Drake. It's intentional. The article clearly states that it is providing "reasons to get excited" and it does a good job of that. But it's worth mentioning the negatives. As The Walrus stated earlier, Drake does not have a good history of staying healthy. Many speed players have this issue. So, it is often beneficial to use them on plays where they are less likely to get crunched. I think Gase has tried to limit Drake's plays to those where he doesn't let LB's and S's get a great shot on him. Most of his plays are designed to go towards a sideline push out of bounds. It makes sense, because those are also areas where his speed can be extremely useful since they are less heavily covered, so if he beats one defender he gets lots of space. But also it tends to minimize the ferocity of his tackles. Teams know this, and play him to be a typically outside running guy.
Also, his pass protection can still be improved. It's not bad really, but most young RB's need to improve their pass protection. Also, his blocking is nothing special, and he cannot play FB. Drake is strictly a tailback with flexibility as an additional receiver.
In Denver, Gase used speed to create mismatches. Demaryious Thomas, Julius Thomas ... he liked multiple speed guys on the field at the same time. By adding speed in Julius Thomas to pair with Stills, he has that in Miami. But given Thomas' history of injuries (worse than even Koa Misi), I think it's fair to say that both Kenyan Drake and Jakeem Grant will get plenty of opportunities to become a speed chess piece for Gase this year.