Not sure what stats they are using. Tie Avengers, at least in the PC games, are much faster than even A-Wings. I could go with a SPD of 4 though. The Tie Defender is a bit faster, has Ion Cannons and also slightly stronger shields than the Avenger. The Speed boost is pretty big. I think BOTH can be mounted with the mini-tractor beam but let's leave that alone for now. That could be a fighter specific upgrade.
Tie Avenger
Speed 4
Hull 4 (More than Ties or Tie Interceptors but same as A-Wing but less than X-Wing)
Squadron Dice = 4 Blue
Anti-Ship Dice = 1 Black
Escort
Counter 2
Tie Defender
Speed 5 (Third Collector adds speed to the fighter)
Hull 5 (Better shields boost the Hull by 1)
Squadron Dice = 4 Blue
Anti-Ship Dice = 1 Black
Escort
Counter 2 or 3
Making the Defender Counter 3 would be a big boost too.
Tie Phantom
Speed 4
Hull 4 (More than Ties or Tie Interceptors but same as A-Wing but less than X-Wing)
Squadron Dice = 3 Blue
Anti-Ship Dice = 1 Black (Not sure what these were armed with)
Grit
Counter 1
Stealth 1 (Causes attackers to re-roll one attack die, defenders choice)