Thomas Vermaelen appears in danger of losing his first-team place for good. And if he isn't, he certainly should be.
In fact, the Gunners should part ways with Vermaelen in the early days of this summer's transfer window. Recent rumours suggesting a £15 million move to FC Barcelona, are almost too good to be true, for both Vermaelen and Arsenal.
That's because the Belgian has endured a spectacular fall from grace. In truth, this author has never felt Vermaelen is a particularly skilled defender.
He is certainly enthusiastic, but his poor anticipation and reckless technique costs Arsenal too often. The depth of his plummet in form this season is not so much surprising as inevitable.
Arsene Wenger's critics will, as usual, lay all the blame at his door. As the manager who signed Vermaelen, Wenger does bear some criticism.
However, his crime isn't the deterioration of Vermaelen's game. It was thinking the ex-Ajax skipper could develop into a world-class centre-back in the first place.
Many may argue Vermaelen has been ruined by Wenger's so-called negligible defensive tactics. However, Vermaelen's flaws rest more with his own frenetic approach to the game.
Liverpool's first goal in their 2-2 draw at the Emirates Stadium in late-January provides a perfect example. At one point in the move, the ball was played across the box and Vermaelen had a simple path to run on and clear it.
However, Vermaelen simply didn't approach the situation calmly. He didn't display any of the composure a quality defender needs.
An assured centre-back would have turned the ball away and accepted a corner. Vermaelen's typically rash decision was his fault alone.
It wasn't due to Wenger's tactics, lack of work on the training ground, or any of the other tired excuses. It was simply due to Arsenal's main defender and captain yet again failing to exude confident authority.
In previous seasons, Arsenal have been able to mitigate the risks of Vermaelen's wild approach. When the likes of Cesc Fabregas and Samir Nasri controlled their passing, Arsenal dominated possession.
Vermaelen simply wasn't exposed to danger as often. During the last two years, that protection has gone, as Arsenal's stylish passing has faltered.
Vermaelen's obvious deficiencies have therefore been revealed more often. The problem for him is that Arsenal's other centre-backs are outperforming him.
Laurent Koscielny's early-season form was littered with calamity. Yet his recent return to the back four has inspired consecutive clean sheets.
The main reason is the one thing Koscielny can do that Vermaelen can't. The Frenchman is better at reading the game.
His anticipation allows him to be in place to attempt to thwart attacks. Vermaelen usually has to scramble to react to developing danger.
In Arsenal's 2-0 win at Swansea City, one of the Swans' best chances showed what Koscielny adds to the defence.
What is clear is that Koscielny's quick reactions disrupted Rangel's goal-scoring attempt. As the Swansea move developed, Koscielny took a look across at the advancing Rangel.
So even after he turned back to the middle, Koscielny had an idea where the next forward pass was going. That meant when Rangel received the ball, Koscielny had already shifted across before the shot.
Koscielny is not considerably quicker than Vermaelen, even over short distances. Yet his superior skill anticipating the flow of play puts him in better positions to defend.
Of course, Kosicleny still has issues. He is often too timid in direct physical challenges, and his penchant for misfortune in alarming.
However, his anticipation is enough to make him a safer alternative to Vermaelen. Arsenal's struggling skipper can't even compensate with leadership and organisation.
In both those areas, he is being usurped by Per Mertesacker. The Germany international, who is too often made the scapegoat, exudes more authority and savvy than Vermaelen.
Television pundits were too busy to praise Mertesacker in the wake of Arsenal's near-magnificent comeback in Munich. However, it was telling that all the replays showed Mertesacker, arms waving, directing the movement and positioning of the back four.
It's also no coincidence that Mertesacker has played in every one of Arsenal's 10 English Premier League clean sheets. Arsenal's defence needs Koscielny to produce a consistent run of strong enough form to emerge as the most suitable choice alongside Mertesacker.
If not, then acquiring a more dynamic athlete to partner the slow-turning German has to be a transfer priority. Either way, Vermaelen could find himself the odd man out.
The Guardian recently reported that Wenger won't bring Vermaelen back into the team simply because he's captain. Based on how the season is developing for Vermaelen and Arsenal's other defenders, this should be Vermaelen's last campaign for the Gunners.