Thomas returned from the Africa Cup of Nations on Thursday and was put on a substitute in Arsenal’s 2-0 defeat in the semi-finals of the EFL Cup against the Reds.
He came on in the 74th minute and by the end of normal time he picked up two yellow cards to get sent off from the game.
The Ghanaian will now miss Arsenal’s Premier League clash against Burnley, but Sinclair refused to blame the player for what happened.
He stressed that given he just returned from Africa, the midfielder should never have been on the pitch on Thursday night, even for a bit-part role.
The former midfielder insisted that fatigue meant that he made the wrong decisions and Arteta made a big mistake by playing him hours after he returned from international duty.
Sinclair said on talkSPORT: “I don’t blame Partey, I think it was a young manager’s decision.
“He just travelled back from Africa, I think he got back at noon. He was fatigued, he should not have been on the pitch.
“He shouldn’t have been playing that game.
“The first tackle, whether that was a yellow card or not doesn’t matter as that’s done and you don’t make the next challenge.
“But that’s fatigue and his decision making was all wrong.
“As soon as you are fatigued one of the first things that goes is your decision-making skills.
“Again it points to the obvious. You have seen Arteta make this mistake with Partey in the north London derby a year ago.
“He was out injured, he rushed him back into the game, he had not really trained with the team, he played, he picked up an injury and he was out for months.”
Arteta’s midfield options are limited ahead of their game against Burnley due to Thomas’ red card and their decision to loan out Ainsley Maitland-Niles.
