Not entirely sure why passing a String instead of an int fixes this..

Changelog.txt

@@ -10,6 +10,7 @@ Key:
 Version 1.3.06-dev
  + Added permissions check to skill functions
  + Added API functions for obtaining offline profiles & profiles via player names
+ = Fixed bug where {0} would be displayed in front of your power level in mcstats
  = Fixed mmoupdate not being useable from console
  = Fixed bug with repairing wooden tools
  ! Changed mcremove to no longer kick players when they are removed from database

src/main/java/com/gmail/nossr50/commands/general/McstatsCommand.java

@@ -28,7 +28,7 @@ public class McstatsCommand implements CommandExecutor {
         CommandHelper.printCombatSkills(player);
         CommandHelper.printMiscSkills(player);
 
-        player.sendMessage(mcLocale.getString("mcPlayerListener.PowerLevel", new Object[] { PP.getPowerLevel() }));
+        player.sendMessage(mcLocale.getString("mcPlayerListener.PowerLevel", new Object[] { String.valueOf(PP.getPowerLevel()) }));
 
         return true;
     }