Some more info about SMSG_ARENA_TEAM_ROSTER structure.

src/game/ArenaTeam.cpp

@@ -304,27 +304,34 @@ void ArenaTeam::Roster(WorldSession *session)
 {
     Player *pl = NULL;
 
+    uint8 unk308 = 0;
+
     WorldPacket data(SMSG_ARENA_TEAM_ROSTER, 100);
     data << uint32(GetId());                                // arena team id
-    data << uint8(0);                                       // unknow 3.0.8
+    data << uint8(unk308);                                  // 308 unknown value but affect packet structure
     data << uint32(GetMembersSize());                       // members count
     data << uint32(GetType());                              // arena team type?
 
     for (MemberList::iterator itr = members.begin(); itr != members.end(); ++itr)
     {
         pl = objmgr.GetPlayer(itr->guid);
 
-        data << uint64(itr->guid);                      // guid
-        data << uint8((pl ? 1 : 0));                    // online flag
-        data << itr->name;                              // member name
+        data << uint64(itr->guid);                          // guid
+        data << uint8((pl ? 1 : 0));                        // online flag
+        data << itr->name;                                  // member name
         data << uint32((itr->guid == GetCaptain() ? 0 : 1));// captain flag 0 captain 1 member
-        data << uint8((pl ? pl->getLevel() : 0));       // unknown, level?
-        data << uint8(itr->Class);                      // class
-        data << uint32(itr->games_week);                // played this week
-        data << uint32(itr->wins_week);                 // wins this week
-        data << uint32(itr->games_season);              // played this season
-        data << uint32(itr->wins_season);               // wins this season
-        data << uint32(itr->personal_rating);           // personal rating
+        data << uint8((pl ? pl->getLevel() : 0));           // unknown, level?
+        data << uint8(itr->Class);                          // class
+        data << uint32(itr->games_week);                    // played this week
+        data << uint32(itr->wins_week);                     // wins this week
+        data << uint32(itr->games_season);                  // played this season
+        data << uint32(itr->wins_season);                   // wins this season
+        data << uint32(itr->personal_rating);               // personal rating
+        if(unk308)
+        {
+            data << float(0.0);                             // 308 unk
+            data << float(0.0);                             // 308 unk
+        }
     }
 
     session->SendPacket(&data);