The only prospect involved in the White Sox and Padres deal for James Shields is 17 year old INF Fernando Tatis, Jr., who the White Sox signed during the 2015-2016 July 2 International Free Agent period for $700,000. Tatis was not ranked among the 47 prospects to which former FanGraphs writer Kiley McDaniel ascribed hierarchy on his 2015 J2 Sortable Board and was not on my top 10 International Prospects list from that time. He’s blown up a bit this Spring and is one of the more interesting bats in Extended Spring Training.

As an amateur, Tatis lacked physicality. He was clearly underdeveloped compared to his peers, and was bereft of the bat control and strength in his hands that are required to really drive pitches in various parts of the strike zone, especially for a prospect that profiled, at the time, as a likely corner infielder. Tatis’ frame had projection though, and a rather significant amount of it considering his age and bloodlines (Fernando, Sr. had one of those jean-selling bodies in his prime).

The Fernando Tatis, Jr. we’ve seen here in Arizona for Extended Spring Training looks very different. Tatis has already made significant physical progress — the only video I have of Tatis right now is his at-bat against Brady Aiken from last week, which starts at about the 2:00 mark, but you can at least get a look at him singling there — and it’s made a huge difference in his overall play.

He has displayed improved control of his body, is making a higher quality of contact and has just generally become explosive enough that the sentiment among evaluators out here is that Tatis has a solid shot to remain a shortstop. His routes to ground balls, his hands and actions have all been good and project to be of Major League shortstop quality and he has a plus arm. He’s currently an average runner, which will be fine for short if he can maintain that speed, but of course at just age 17 he’s going to keep growing and probably slow down some.

While he can play there for now, the chances of Tatis remaining there in his prime are somewhere between “moderate” and “unlikely” on the Continuum of Shortstopdom. Should he have to move it will likely be to third base where, given those shortstop-quality actions, his glove would arguably project as plus.

Even since just the early part of Spring Training, Tatis has improved his footwork in the box, is tracking pitches better and using the entire field. He still hasn’t displayed the kind of wrist/hand strength that’s indicative of impact power and he really only projects to have about average pop at maturity, but if he can stay at shortstop that’s going to be just fine. The bat projects to average as well. A 50/50 hit and power combination from a shortstop, even one that is just passable defensively as Tatis would likely be, is value on par with an average regular. Given Tatis’ age and proximity to the Major Leagues, there’s obviously a substantial amount of risk here, which suppresses the Future Value grade below.

Hit: 20/50, Raw Power: 40/50, Game Power: 20/50, Run: 50/45, Field: 40/45, Throw: 60/60, FV: 40

The other return on the deal is 26 year old RHP Erik Johnson. Johnson’s four pitch mix — fastball, slider, changeup, curveball — is mediocre. He’s experienced fluctuations in velocity during each of his abbreviated big league stints and this year the stuff is down. Johnson has been about 89-92 this year with below average control that often leaves his fastball either in the top half of the strike zone or out of it altogether.

His slider is above average, in the low-80s and Johnson finds his spot with it more regularly than the fastball. The changeup will flash above average from a pure movement standpoint but Johnson’s arm action is different on the change and big league hitters have been able to identify it. Because of this, Johnson deploys a back foot slider as his go-to weapon against lefties for swings and misses. His curveball sits in the low-70s and is a slower, deeper, more infrequently used change of pace used for early count strikes.

Johnson, who has been sent to Triple-A El Paso, gives San Diego an arm to run out there every fifth day for the rest of the season if they need it and doubles as a reclamation scratch-off ticket because of his interesting pedigree. PETCO Park should provide a bit of a cushion should Johnson fall into San Diego’s rotation.