Highlighted reports are within 1 standard deviation of the sample. This means the tps numbers are more typical. Reports not highlighted are more likely to be bogus, or otherwise considered somewhat of an outlier.
Only the top 200 reports per class are shown. However, average tps and standard deviation is based off of all reports in the index.
Some of the very highest tps scores are not always genuine(although some are genuine). Reports which seem to be significantly above most of the others are often the result of of either a poorly merged combat log file, or the user tampering with the combat log to inflate numbers.