De Leon gave up four runs on two hits while walking two and striking out one in 0.2 innings during his spring debut against the Red Sox on Thursday.
It was a rough start to spring for the 24-year-old, who missed the beginning of camp with tightness in his back. The good news is the prospect said he felt normal, but he just couldn't throw strikes for the most part. De Leon will look to bounce back as spring progresses and he continues to compete for a rotation spot.