According to Trevor Wittman, he actually tried to stop Nate Marquardt's UFC 188 fight before the end of the second round, but wasn't allowed to.
In MMA, a cornerman stopping a fight is very, very rare. Unlike boxing, the people advising a fighter are almost guaranteed to let a guy go out on his shield rather than protect their fighter. That's why it was so surprising (in a good way) when Trevor Wittman stopped Nate Marquardt's UFC 188 fight with Kelvin Gastelum after the second round of a one-sided beating. What's even more surprising though is that Wittman actually tried while the round was still going on, but his request was ignored.