Essentially a two-pitch pitcher, Fields relies on his fastball, and for good reason. His four-seamer produced an excellent 40.1 O-swing%, 53.1 Zone%, and a 13.8 SwStr%, and pairs well with his curveball. Fields relies on his fastball for swings and misses, and is his go-to pitch late in counts when he needs a strike as well.
Fields uses his knuckle-curve as a free strike early in the count and as a complement to his fastball. Opposing hitters only swung at his curve 24% of the time overall and only 33% of the time that the curve was thrown for a strike. Fields does not get many chases nor swings and misses on the curve, which hurts his overall strikeout numbers. But hitters have had very little success against the curve, with only one extra-base hit against it in 2018.
Thrown only 33 times in 2018, Fields uses his changeup sparingly. Opposing hitters had very little success against the pitch in their limited opportunities last year, and it did produce a 12.1 SwStr%, which was up from previous years. But the changeup is a clear afterthought for Fields.