I don't agree there.
Hughes' try was because he stepped inside 3 forwards, and then Simpkin didn't cover inside hard enough. That's not a fatigue thing, that's assuming your inside man has his zone covered and you don't need to push in; he had enough time to do it. The main error was from Stefano, who covered the inside too late and was beaten by another right foot.
Second try Kelma was a bit fatigued to get back to marker yes, but Brooks just watched Hughes run through and only reacted once Hughes was away. If the guy is going to make a line break you are probably better off just making a tackle at the first opportunity, even if giving away a penalty. Instead Brooks just watched him go by.