A Pitcher's Stuff
noun
Your sphere might is the force you command over a sphere or ball… in this case, a baseball, making this a pitcher’s stuff.
If you’re not familiar with this baseball term, we recommend giving it a google. In short, it refers to a pitcher’s pitches, judged by how inherently hard those pitches are to hit.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
野球のシーズンが到来する春に近づくにつれて、あの投手の球威は益々増しています。
As it gets closer baseball season in spring, that pitcher gets better at his pitches.