The Bees go to Old Trafford on Sunday.
Frank said, "It's incredible how much scrutiny he's had to face.
"As a head coach, I acknowledge how it feels to be in a situation like this. I think it is too much.
"He's clearly a good coach, he's won two trophies in two seasons. But I understand how it is: if the team wins, the head coach is absolutely fantastic; if the team loses, the head coach is absolutely s***! Whereas it's probably somewhere in between.
"It's never only the head coach, or the players, or the fans, or the board - it's a combination of all of these things."
On United's current form, Frank also stated:
I've experienced it too many times in my career: we face a team that has lost three games in a row but they come out absolutely flying. Then, other times, we play a team that has won five games in a row but we beat them.
"I don't really pay too much attention to.
" The only thing I focus on is how we can make sure we are up there and how we can do everything we can to perform and come out flying - and hopefully we score early again."