- Get a stopwatch,
- Count the time you spend in the spreadsheet just for synching up versions
- Count the time you spend repairing broken versions
- count the number of times people shout in the hallway "i'm editing main.c!, just to make sure nobody else is right now!".
- count the number of complaints you get from customers because their bugfix contained other changes
- count the time delay of release just because you were unable to synch up the versions
- Make a powerpoint with this data, compare with how vcs would work.
- Show management