The Baggies’ disciplinary record has been woeful in recent weeks with Ismael’s side collecting six red cards in their last 12 outings.
That lack of control means Albion will be without Sam Johnstone, Alex Mowatt and Cedric Kipre when they travel to take on promotion rivals QPR on Saturday.
“Something has to change with the red cards,” Reach said.
“You have got to toe the line. The manager likes to play with a high press and he likes to play with intensity.
“You have to show that but once you get a yellow card you have got to be careful because as soon as you get sent off it changes the game, especially with the way we try and press.
“There is always going to be a man free, free players and free gaps which opposition teams can exploit.
“We have got an important game coming up on Saturday and we have got three players missing which isn’t good. The manager wants to be able to pick his strongest team.”
Albion will have four centre-backs missing at Loftus Road with Kipre suspended, Semi Ajayi at the African Cup of Nations and Dara O’Shea and Kean Bryan injury. For the first time in his career, Reach played as a central defender in the win over Reading last month.
And he says he’ll happily play there again on Saturday if that’s what Ismael wants.
“I enjoyed it – that was a positive moment for me playing there,” Reach said when asked about his performance against the Royals.
“The manager has got decisions to make now with Cedric out as well and we’ll see what he goes with.
“Some of it will depend on what QPR do, who he thinks might be able to come in and do a good job.
“If that’s me I’m ready to go and I will fill-in and do my best.
“And if it’s not me then one of the other guys will be raring to go and I’ll be ready to come on and make a difference from the bench.”