I looked it up and the Rockies AAA club plays in Colorado Springs, so maybe Francis will be used to the high altitude.
Look at his stats from there:
7 Starts, 41 IP, 35 Hits, 7 BB, 49 K, 3 HR, 2.85 ERA.
That is only triple a, but damn his numbers are impressive. Only 3 HR in 41 IP, a 0.7 HR/9 in high altitude! His K rate is incredible. The more I look stuff up about Francis, the more I think you should take him.