Kelly A Manners was the sole producer — amongst several executive producers and associate producers — of Torchwood: Miracle Day. His own long experience in the American television series is key to understanding key staffing decision on Miracle Day. Many key figures on the American team had worked with Manners before.
Manners has long worked with Joss Whedon, serving in a variety of capacities in the Buffyverse and having produced Dollhouse, which featured Dichen Lachman. He appears to have brought other Whedon alumni into Torchwood, including people like associate producer Skip Schoolnik, costume designer Shawna Trpcic, and key make-up artist Todd McIntosh, Additionally, Lion Visual Effects, Inc. — the visual effects company for Miracle Day, had worked with Manners before on Dollhouse.
Manners has enjoyed a long career, in which he's worked on some of the most iconic American shows of the last two decades. He was a 1st and 2nd AD on Wonder Woman during its final season. He also worked as a (sometimes second unit) 1st AD on The Dukes of Hazzard. He served as a unit production manager on the Star Trek: The Next Generation episode "Coming of Age". Just prior to joining the crew of Buffy the Vampire Slayer, he was a 1st and 2nd AD on Space: Above and Beyond.
He joined the crew of Buffy as a 1st AD, as well, but over time he rose to the position of co-producer, before he jumped to Angel as full producer. He was with Angel for its entire run. Since the demise of Angel, he's gone through several series that have failed to gain an audience, including Point Pleasant, Pepper Dennis, K-Ville, and Dollhouse. He came to Torchwood after a very brief stint on Leverage.