He reckons Flahavan was unfairly challenged by big John Akinde.
This happened moments before Josh Yorwerth fouled Curtis Weston which led to Barnet being awarded a penalty.
The spot-kick was calmly put away by Akinde for 3-2, something he was not known for during his 18-month spell at Crawley.
Then Barnet were handed a fourth goal two minutes later when Simon Walton hit an attempted clearance against Lewis Young and the ball flew backwards into the net.
Yates said: “I think it’s a foul on Darryl to be total honest. I’ve seen it a few times and I think it’s a foul.
“The referee said to Jimmy that Darryl wasn’t in control of the ball but if you have a 6ft 4ins centre forward smashing down on you then it’s not easy to be in control.
“So I thought it was a foul but what was Josh doing diving in? Or not diving in, but going to ground? He was in control of the ball and the lad has just bought a penalty.
“It was rightly given but I think it should have been a free-kick in the first place.
“You have to be ruthless with teams and be tough in this league, no matter what. I just felt we let one or two of them bully us and that’s not what we set out to do.”
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