First of all, you haven't even tried to mod Oblivion correctly. The use of Nexus Mod Manager is discouraged by the nexus staff itself. Second, do you have Oblivion GOTY or GOTY Deluxe? Both are up to date, so you don't need the patch, however Deluxe includes DLCs that have their own unofficial patches and it may be the reason why is telling you about the missing masters, since the unofficial patches are plugins that rely on the DLC masters. Third, you should either keep using Wrye Bash or migrate to Mod Organizer 2. And read the tutorials given by the managers. You may as well play the vanilla game for a while, put the settings to the values you want, and then drop OBSE files into Oblivion, and finally start installing the mods the way you want.