The Stats Plugin provide users with stats for the current map. Those stats are not persistent, they are not saved day after day like XLRstats does.
<configuration plugin="stats"> <settings name="settings"> <set name="min_level">1</set> </settings> </configuration>
The skill you earn by killing another player depends on the victim's skill. If you kill a high skilled player you will earn more skill points than if you kill a noob.