One of the problems with mid-sized companies is that they're big enough to need to have separation of responsibilities and processes but not quite big enough where they have the time, resources or manpower to put processes and the tools that enforce those processes in place. And that's if they at least recognize the issue in the first place.
By the way, the answer in the situation you've detailed is to include the administrators within the project and assign the installation task to them within the project plan. Even if it just seems like a "bookkeeping" change (and it is), it serves the purpose of highlighting who is responsible.
Also, if an install is critical enough, don't be afraid to escalate the issue as high as it needs to be up the management chain. If the sysadmin manager isn't available/responsive, then go to their manager (you might need to go up in parallel on your own management chain first). If you're hunting down the sysadmins on your own, it basically means that management isn't doing their jobs and/or the project really isn't a priority to them.
By the way, the answer in the situation you've detailed is to include the administrators within the project and assign the installation task to them within the project plan. Even if it just seems like a "bookkeeping" change (and it is), it serves the purpose of highlighting who is responsible.
Also, if an install is critical enough, don't be afraid to escalate the issue as high as it needs to be up the management chain. If the sysadmin manager isn't available/responsive, then go to their manager (you might need to go up in parallel on your own management chain first). If you're hunting down the sysadmins on your own, it basically means that management isn't doing their jobs and/or the project really isn't a priority to them.