A multiplier would still be linear. A non-linear function is one that changes slope at different times during the output...simply adding a multiplier doesn't create that effect. If an extra percentage of Usage doesn't always mean the same thing in terms of how it impacts the team, then it's a non-linear factor and dividing it by PER will still yield a non-linear function...no matter what multiplier you put on it. In which case, just looking at Usage/PER is meaningless unless you know where the value of Usage changes and how.
Since Usage is on a completely unrelated scale from PER and, as andalusian said, incorporated into PER, it isn't at all clear that simply dividing Usage by PER is ever meaningful. Any more than dividing steals per game by winning percentage is particularly meaningful.
It would be linear in the sense that the multiplier would add a linear effect, so long as you stay consistent in your equation. I should hope that any advancement of statistics is linear in its application. Also, I'm noticing a correlating trend, not some sort of mathematical fact, and I'm asking for it to be explained. Thus far, all I have is a lie about how a 1.0 Usg/PER ratio is close to a mean. Clearly, it isn't.
Any statistic is on an unrelated scale from PER. That seems obvious, doesn't it? Do you work with numbers for a living?
You were wrong on your 1.0 Usg/PER ratio assumption, but that's not a big deal to me. That another poster seems stuck on your false assumption and has ended up hijacking this thread is unfortunate, but I do feel that there is value in looking at the components of an equation, and how they may impact the answer of that equation.
I'm not saying that usage is or is not a valid statistic; I am saying that it may seem to play a role in PER inflation, that it is a part of the PER equation, that it may be able to separate players of a similar PER in terms of their on-court value, or even (gasp!) their "usage" by their own coach.
That's all I'm asking in my brainstorm. The non-linear answers that are all over the board, yet don't attempt to refute the Usg/PER statistic, don't surprise me.