The Rockies have fallen back to earth and are a fade on the road especially at Arizona.
Colorado has lost 37 of its last 51 away games. The Rockies are 1-5 in their past six games at Chase Field. 
Arizona is going with Merrill Kelly, who has a 2.59 ERA. He's pitched well in four of his five starts. Colorado is pitching righthander Ryan Castellani, who just got battered by the Astros in his last start giving up five earned runs and eight hits in 5 2/3 innings.
The Diamondbacks are 0-7 versus southpaw starters, but 13-9 when facing righthanders. 
Arizona also is 15-3 the past 18 times as a home favorite.