Manager Arsene Wenger has repeatedly expressed a need to offload several outfield fringe players deemed surplus to requirements with goalkeeper Wojciech Szczesny the only senior figure to depart so far this summer.
Gabriel joined the Gunners in January 2015 for £13.5m but he struggled to hold down a first-team place, starting just 37 Premier League games with his only goal coming against Bournemouth 11 months after his arrival.
Despite switching to a 3-4-2-1 system in April, Wenger deemed the centre-back surplus to requirements given Rob Holding, Per Mertesacker, Laurent Koscielny, Shkodran Mustafi, Nacho Monreal and Sead Kolasinac can all fill the defensive positions.
Wenger admitted previously that Gabriel’s lack of English was a significant problem following his arrival given he barely spoke a word and has a problem communicating with his team-mates.
Although the 26-year-old underwent regular lessons, it is understood there was only a marginal improvement in his vocabulary.
Valencia released a social media teaser hinting at Gabriel’s unveiling last night and the La Liga club are expected to confirm his transfer within the next 48 hours.
Arsenal will now turn their attentions to moving on other players including Kieran Gibbs, Lucas Perez, Mathieu Debuchy and Calum Chambers.
Gibbs has attracted interest from a host of clubs including Watford, Newcastle and Brighton but, as Standard Sport revealed on June 8, Arsenal may be required to lower their £15m asking price.
The left-back is in the final year of his contract at Emirates Stadium and is assessing his options after being told his opportunities would be limited.
Perez is in a similar situation with his agent repeatedly voicing his frustration at Arsenal’s unwillingness to take a significant hit on the £17m they paid Deportivo La Coruna to sign him just over a year ago.
Deportivo are interested in re-signing the striker but the two clubs remain a long way apart in their valuations. Newcastle’s attempt to take Perez on loan was rejected with the Gunners demanding a permanent transfer.
Wenger is equally defiant over the futures of high-profile trio Alex Oxlade-Chamberlain, Alexis Sanchez and Mesut Ozil.
All three have entered the final year of their contracts with Chelsea eyeing up a £35m move for Oxlade-Chamberlain, who has so far indicated he will not sign an extension with Arsenal.
Sanchez and Ozil are also yet to commit – although Ozil is thought to be much closer to doing so – and Wenger yesterday repeated his stance that the trio would remain at the club, albeit hinting that on occasion the outcome of such situations is not always predictable.
Arsenal have been determined not to repeat history by selling a big-name player to a domestic rival but when asked whether he was surprised Chelsea did just that by allowing Nemanja Matic to join Manchester United, Wenger replied: “Look, every club has a different policy and you have to respect that.
“You analyse the age and the money you get, and I don’t say I never do it because I did it as well with Robin van Persie [in 2012] at the time when he was [near] the end of his contract and Man Utd played good money. It’s not ideal because you strengthen your opponent and you weaken your team.
“Do I regret selling Van Persie? I just say I do not say never, because every situation is different and sometimes you are in a position where you have as well to consider the financial aspect of the situation.”