If they use sales numbers to give a rating then use those ratings as a basis for a reduction in force or a termination a lawsuit can be successful because garbage in is garbage out. Sales numbers should be objective but of course they are not here. The perfect explanation for that is how come some president club winner's do not get 3's but reps in the bottom were getting 2's. Just look at Long Island's ratings at the end of 2011. Bad business decisions are not actionable but disparate treatment certainly is actionable. Don't worry I won't starve.
There would not be an good employment case if the data were used for a RIF as they can use any data that they want, even bad data, to make general business decisions, even bad business decision that are ultimately unfair.
And your example of the PMP is just ridiculous.
The only way that any US employer can be found to be liable for the results is that if they, with NO BASIS, have employment practices that arbitrarily and capriciously have deleterious effects on a single or in the case of a group of individuals, share a certain demographic classification.
The offer letter that you sign when you join a US company says that you are "Employed at will of the employer". Which means that you, as an individual, can be fired at any time for almost any reason. If you are in a "protected class" (Minority, over 50, disabled) then a little more care will be taken (PIP) and maybe you will be offered a package where you sign a general release so that you cannot sue.
If you are fired in a group, like a RIF, you have almost NO good options as like I said above, unless you, as a group, can claim that they fired you ALL do to some distinguishing characteristic that you ALL EACH share. But that is nothing besides that in any employment law or precedent in the US.
So, they can us any data that they have to make decisions to fire anyone as long as it is applied equally to anyone. Then the only way that you may have a case if you think that they don't use it fairly is to make the case that they used the data against you because you are a member of a protected class.
In your case, if they don't like you because you think that you are an employment lawyer because you slept in the Holiday Inn last night, and fire you. You have no case.
As I said, it isn't against the law for a company to be poorly run, so there would definitely not be wrong be wrong in firing you. You are a complainer, aren't very smart but think that you are.