Mobility is notebook graphics card so that's why it is off as someone already mentioned.
The site is pretty accurate as long as you understand it is just a single benchmark.
Better cards are listed first in order if they are in the box on the chart? From the link you gave Discrete: HD 4870, 5770, 4890, 5830, 6770, 6790, 7750
If that is the case, then why is the 4890 after the 4870? I don't think you can make that conclusion.