At 12:00 the clock should be at the top of the hour no matter the time zone.
I believe the default time when an arena gets reset is 12:00. Unless the arena is reset and comes back up EXACTLY at the top of the hour, the game time (minute hand) will never match real time unless someone manually goes in and changes the game clock - which will not happen anywhere other than custom arenas, the AvA and the Special Events arenas.
And whats with the Arena reset? 4 mins to arena change is over in like under 3 minutes.
I'm rarely on when an arena is reset. Are you starting your timer as soon as the first reset warning pops up, or does it take you a minute or so to notice the message?