Trinidad stops him. Just a better fighter. Martinez has too many defensive flaws and it would catch up with him. Martinez was always kinda overrated to me.
I'd definitely give Martinez a better chance at 160 due to Tito being rather 'labored' at 160 lbs. He didn't have the same sharpness on his punches that he did at 147 and 154, and Sergio did appear to carry 160 better. At 154 with Trinidad where he was probably at his best, I definitely agree he takes Martinez.