I knew what you were gonna post before I even clicked. Too predictable.
The thing is that your perfect boxer will ALWAYS have 50% chances of winning upon playing against boxers of your level.
However an account lvl 99hp 80 att 80 def and 60 str will most likely have over 50% chances of winning when it plays against boxers of his level.
Rather than giving your account low strength. Give your account HIGH HP.
Those are the stats a boxer should have as you know. But with 99 HP and low strength and some low stats ( like 60 strength 70 att 90 defence) you could be at lvl 90 and you could fight some level 95+8.
There is a nice amount of boxers at lvl 100-138
Having low prayer and summoning and staking higher leveled accounts,can help you get some stakes without lying about your stats or getting some hiscore tricks.