I have seen Diaz twice this season, both in the past 10 days, for a combined two innings of work. He's looked like a big league reliever in both looks, completely overwhelming his opposition with a three-pitch arsenal. In my second look, this was the sequence to one right-handed batter: 99 mph fastball with run; 87 mph slider with two-plane break; 99 mph fastball with run on the outside black for strike three.

The success is coming from his fastball, a true 80-grade offering that plays to its fullest potential, and recently discovered ability to throw strikes. Diaz established the fastball in both outings, throwing it for called strikes. The pitch doesn't flatten out at any velocity, including 99 mph, which is rarity. Establishing the fastball allowed his two other offerings to play up. The slider became a swing-and-miss offering in, as well as outside, the strikezone. He will throw it glove side consistently. The changeup is most pitcher's fastball, and the bottom will fall out at times.

I would fast track Diaz to the major leagues, because he may be the best reliever in the Angels organization right now. The stuff is major league ready; there's no projection in the body or arsenal, so there's no need to waste bullets in his arm. Move him up one level at a time to see if he can keep throwing strikes with the fastball.