After reading pretty much all I could find on the OC hire, these seem like the 3 best reasons to feel good about this hire:
1. He IS NOT a former boss, mentor, friend, or even peer to Philbin. IMO this clarifies the chain of command for the ENTIRE TEAM and is the main reason I didn't want Kubiak to begin with. (It's too easy to argue that someone like Kubiak is equally or more qualified to be the head coach than Philbin which creates chain of command issues like I suspect happened with Sherman.)
2. He started at QB in college for 3 years, has worked with numerous successful QBs and is proven QB improver. (There's plenty of citations to this fact on this forum already) Furthermore, he decided to coach Ryan Tannehill instead of Matthew Stafford. Not only is that good news for RT's growth as a QB, but it's also a ringing endorsement of Ryan Tannehill from the guy who will be coaching him.
3. He is well respected around the league and has experience in the Modern NFL offense. Not only did he coach under Chip Kelly last year but he also ran a pro-style offense as OC in college.