Considering how difficult it is to place 1st to 3rd in the daily Black Market Fights my suggestion is the buffs should be increased.
If you win 1st place 5 times the buff is +10 attack which is the same as attaining the rank of gladiator or just reaching level 10.
If you win 1st place 50 times the buff is +50 attack which is the same as winning 910 arena fights.
The Pit Fight Achievements seem like real accomplishments and many of the others you get just for playing normally.