Chris Mitchell takes an in-depth look at Luis Severino. Two thinks stand out to me. First:

Let’s look a bit more closely at Severino’s home run numbers. Although he’s not much of a ground ball pitcher, Severino does a good job of limiting the damage on the balls hit in the air against him. For one, he induces more than his share of infield flies. According to Minor League Central, Severino’s infield fly ball rate was higher than his league’s average at every stop since High-A. But more importantly, his home run to outfield fly ball ratio has been consistently lower than league average. Between this year and last, just 4% of Severino’s fly balls to the outfield have left the park, compared to an average of roughly 8%. All of this is to say that Severino doesn’t allow a ton of hard contact.

This reminds me a lot of Matt Cain. In his best years, he was a fly-ball pitcher who didn’t allow home runs. His fastball tended to drop less than what batters expected, and they tended to get under the ball. If Severino’s upside is Matt Cain, the Yankees should be very happy.

Second is a contrary opinion from Keith Law:

Severino is a future reliever. You can’t stay a starter without using your lower half at all. He has a great arm, loose and easy, but I can’t name an MLB starter who uses his lower half as little as Severino does – nor do I think you can truly command your fastball if you’re all arm and no legs.

I wonder if the all arms delivery fools batters? I suspect it’s rare for a pitcher to use mostly his upper half, since legs are important to generating speed. You can see video of his delivery here. He pushes with the leg, but it’s more like a short kick than a full push. He’s throwing 94 in the video, so maybe he just gets the same acceleration from a fast kick as he would from a long push. We’ll see if the unorthodox delivery fools major league batters as much as minor league hitters.