Hi,
I'm a Sysadmin, and I've been a grumpy one through a larger part of my 15 years experience.
My main issue was that Developers were acting like Users: they don't care about what you have to deal with, they want things to 'just work'.
In return, I've treated them like children, in some instances yelled at them when they did dumb stuff. I've tried to educate them when possible, and was angry when the education didn't stick. At the time i was the 'King of the Hill' type of sysadmin - natural leader of a very small and tight team, kind of irreplacable, and with enough years in the company behind me to consider myself as a demi-god.
When I switched companies, I came across better developers. Some had decent sysadmin skills, but the main difference was that they actually took interest in how things worked past the 'git push', and when I asked / required them to make some changes that would make my life easier, they listened, discussed and adopted when appropriate.
With those same guys, I took interest in what they were doing, what their actual job was and came up with ideas that would make things easyier and run smoothly on both ends.
After a while I figured out that they weren't actually better developers - they were better people.
(Also, I figured out that being grumpy was not the best approach and that patience, kindness and gratitude could get people to do more than snark, humiliation and flame-throwers.)
I guess my point is: you don't really NEED to have sysadmin skills to be a decent developer; what you really need is to care about what sysadmins do - be curious, talk with them and trust them when they say that your brilliant idea won't work in production.