In Hellickson, the Diamondbacks land a 27-year-old starter with a pretty good resume in the big leagues. He struggled in 2014 (13 starts, 1-5, 4.52 ERA, 71 hits, 21 BB, 54 K in 63.2 IP), but might be able to bounce back as he moves to the National League. That said, Arizona's homer-friendly ball park will be a challenge for Hellickson, a notorious flyball pitcher.

The Rays are good at trading core players when their salaries get too high, and they're usually good at recognizing talent from other rosters. Williams is a 19-year-old outfielder with a fairly high ceiling, especially in the power department. He's a good prospect for down the road. Velazquez is also a young prospect with upside, and might eventually become Tampa's shortstop of the future--due to his great glove and base-stealing ability. He's 20 and also several years away from the bigs.

Hellickson's fantasy stock could go either way. If he adjusts to his new surroundings, he could improve upon his '14 numbers but might struggle if he doesn't keep his pitches down in the strike zone (because of Arizona's ball park). He's a pitcher to watch closely heading into 2015. Both Williams and Velazquez should be added to the fantasy radar in keeper leagues, but both are not close to becoming a fantasy factor in the big leagues.