Too early to tell. I would hope that he has a workout for all teams involved. There is one thing definite about Chapman, he has one of the best left handed fastballs we have ever seen in terms of velocity. RJ in his prime matched him, but thats about it. If he is 21, then he could potentially throw HARDER, which blows my mind. He can comfortably sit 96-98mph and can max out at 102-103mph. That's video game fastball right there
But along with that come questions about his secondary stuff and his command. I have heard more conflicting reports from scouting sites and from scouts themselves who have seen him pitch. "He's got a lights out slider ZOMG!!!" "His slider is inconsistent" etc, etc, etc. I dont have any reports on him having a third pitch, although his work in the WBC was out of the pen IIRC, so he may not have needed a third pitch.
What I can tell you is this. If he is 21 yrs old, then his basic package and basic tools is better than any pitcher at his age, period. Left handed, young, 100+mph FB, plus potential slider. Sounds at the very least like a clone of Billy Wagner. But it sounds like teams are going to try him in the rotation and see how it goes for him. He might be worth well more than $60 million, but the unknown quantity plus the lack of workouts has me skeptical that he will ultimately be worth it. Now as a fan, I want to see him in Yankee pinstripes, price be damned! Even if he ends up as Mo's successor, he'd still be worth something