With the Gunners having secured the signing of Germany international Mesut Ozil, it is thought that the Blues did not want to strengthen a side they saw as a direct Premier League rival—instead choosing to loan Romelu Lukaku to Everton.
The decision has left Arsenal short of numbers in attack, with Nicklas Bendtner now remaining at the club as backup to Frenchman Olivier Giroud. The Denmark international released a statement on Tuesday, per BBC, confirming that he would have moved elsewhere before the close of the window if another striker had arrived at the club—a cause of further frustration for all concerned.
In the end, it was Chelsea and Everton who emerged as winners from the situation.
As much as Jose Mourinho would probably have preferred to have kept Lukaku at the club this season, the delays over completing a deal for Ba have seen Chelsea weaken Arsenal as a challenger in the Premier League.
Whether a deliberate policy or a genuine change of heart, the Blues' decision left their rivals in a spot of bother in the closing moments of the window and, as a consequence, Arsenal will play the first half of the campaign with a player that they were happy to see leave the club.
The same, of course, can be said of Chelsea. However, other than the need to continue paying the entirety of Ba's wages, they will not be unduly concerned.
After all, the Senegalese forward is remaining at the club only in the capacity of a third-choice centre-forward, with both Samuel Eto'o and Fernando Torres ahead of him in the pecking order. He will be a useful rotation option but nothing more.
Indeed, when you also consider that Mourinho chose to field German Andre Schurrle centrally in an important clash with Manchester United recently, the prospect of Ba getting a huge amount of playing time this campaign seems somewhat unlikely.
Deadline-day activity is always a risk, and in this case, Arsenal got caught out by their rivals. While the capture of the wonderfully talented Ozil will no doubt ease the pain somewhat, the lack of cover upfront remains a major flaw in the Gunners' squad.
It is a flaw that will cost them over the course of a league season, with their top-four rivals all boasting deep squads in comparison. Their lack of a backup plan, and the cunning of Mourinho, will end up being decisions that are reviewed once more come the end of the season next May.