His campaign was sullied by being caught out by a Joe Bryan free-kick in the play-off final against Fulham, but he had been one of the Bees' best performers prior to that, which has put him on the Gunners' radar.
But what is it about Raya's performances which sets him apart?
David Raya: Brentford 2019/20
Raya proved to be a significant upgrade for a Brentford side who threw promotion away in the closing stages of the season.
Signed from Blackburn in the previous close season, he proved a comfortable fit for the Bees' passing game. In the 2019/20 season he made 32.1 passes P90 with a 71% completion rate, one of the best of any goalkeeper in the league.
And the passes weren't all short, either, with around 55% of them going long. He has the capability to play out from the back but play long passes to the full-backs to progress the ball quicker.
Given how Mikel Arteta's clear focus has been on playing out from the back, as witnessed once again in the Community Shield, and he is looking for another GK who can do that. Bernd Leno is first choice and can play out but it perhaps isn't his strongest suit.
Raya is excellent at that, and has excellent composure, too. But as we see, maybe too much time is spent with modern goalkeepers looking at their competency with their feet. Luckily, Raya is more than adept with his hands, too.
His 16 clean sheets is the second-highest total in the Championship, while his 0.9 goals conceded P90 is the best rate in the league, with a save % P90 of 73.9%.
What will be concerning, however, is the number of Errors Leading to Goal that Raya succumbed to - five in 49 games. That's beaten only by Joe Lumley of QPR (six). There are errors in his game.
But all in all Raya is a more than reliable back-up available for a decent fee. With Emiliano Martinez moving to Aston Villa, it means that a good, reliable replacement can come in and compete with Leno for minutes in some of the lesser competitions.