With the economy in a slump, some companies have been freezing pay raises or even cutting pay for some employees so they can offer substantial raises...

With the economy in a slump, some companies have been freezing pay raises or even cutting pay for some employees so they can offer substantial raises to people who are considered star performers.  As a motivational technique, does this practice seem like a good one to you?  Why or why not?  What could be a disadvantage?