I personally think any motivation anyone gets from those things is short lived and doesn't carry through a season, and that if a person doesn't have the motivation to begin with it can't be artificially created in a way that can be sustained. I think the kind of drive to be elite is either there or not.
My belief is also that the contract year phenomenon is largely overstated. I understand why it seems to be significant, which is because it really stands out when someone plays to a level that elevates his status in a contract year, but far and away the majority of the time t doesn't work that way, but people don't really notice that because it doesn't stand out, so it is easily forgotten or not noticed to begin with.