Huhhh... I 'just' said that the Gladiator actually seems to *benefit* from having huge muscles/extreme++ strength.
The text appears to reflect that, at least.
Here's all the outcomes in the non lethal fights.
http://pastebin.com/QUagNweK
So it looks like you were right.
Here's the lethal ones.
http://pastebin.com/qpfz8VaC
Having big muscles even lets them grab large swords.
On that note, now there's an easily available source of slaves with combat training. The Gymnasium Academy. If you buy enough slaves from them, eventually you get an event that upgrades them in which you can have them all come with combat training. You can make a max of 10K from lethal pit fights, so you'd be able to buy gladiators who die each week and pocket the difference. Wonder if it's worth the effort for a 5K+ profit.