Tommy lost due to poor writing
Hate to say it, but its this.
I mean I GUESS I could by Tommy going so crazy that he let his guard down against his brother and he got caught slipping. (thus leading to hurting his shoulder)
I GET that they wanted to him to "fight till the death" until his brother told him, "I love you Tommy". No doubt, Tommy was not giving up until he heard that or he would have kept fighting.
With that said, they had the matchups wrong. Why have Tommy destroy that one dude in 10 seconds? Why not have Brendon fight him. Then have Tommy fight Koba instead. Make it a bloody war and Tommy is worn out by the time he faces Brendon in the final match.
Tommy destroyed the competition too easily for him to go out like that. They should have matched him with Koba to show he slowed down a little bit.