Roque Mercedes

The D-Backs received Mercedes as part of the return from Milwaukee for Felipe Lopez in July. At 22, he dominated for the Brewers' High-A affiliate at Brevard County before getting promoted to Double-A Mobile after Arizona acquired him. Mercedes has a good low-to-mid 90s fastball and a strong curveball, an arsenal that should help him move quickly through the system in his current relief role as long as his command remains sharp. He may have to start 2010 back at Double-A, but it'd hardly be surprising to see him with the big league club during the second half of the season, especially since bullpen depth looks like a potential weakness for the D-Backs even if they make a couple of additions through free agency.