Liverpool ended up losing the game 4-1 and put their chances of making the top four in jeopardy.
“That is just ridiculous, he is now missing a really important game, a replay against Blackburn when Liverpool have Skrtel out,” Mcmanam said speaking to BT Sport.
“That has put Liverpool under more pressure.”
The red card was the 21-year-old’s first for Liverpool since joining from Bayer Leverkusen in the summer.
The young midfielder-come-defender was sent off for a second yellow card offence in the last minutes of the game.
Can has added to the Reds defensive problems ahead of the FA Cup semi-final tie against Blackburn at the FA Cup on Wednesday.
“It is really upsetting about Emre Can, you need him fit and now he is missing a big big game for Liverpool,” he added.
Martin Skrtel will also miss the mid-week FA Cup clash due to injury.
Can will be available for the Reds next Premier League game against Newcastle United at Anfield.