Martinez proved an inspired stand-in while Leno was out with injury last season, playing a pivotal role as Arsenal picked up a record-extending 14th FA Cup title.
The Argentine made it clear he wanted to stay with Arsenal but insisted first-team football was his priority. And with Leno returning to his No.1 spot, Martinez completed a £20million move to Aston Villa earlier in September.
Martinez has instantly proved a hit in the Midlands, saving a penalty on his debut against Sheffield United and now keeping two clean sheets in as many league games with Villa sat inside the top four with a game in hand.
Though Arsenal have made a fast start to the season of their own, putting in an impressive performance despite a 3-1 defeat to Liverpool on Monday, Adams believes Villa have got the better end of the deal.
"Martinez was incredible in their cup run. He was absolutely sensational," Adams told Astro SuperSport. "What Leno does struggle with, for me, is crosses.
"Arteta’s gone, 'No, Leno is my number one, I like him' and he’s put all his faith in him. But I don’t believe that he’s a top-four goalkeeper.
"Martinez, it was coincidence, everything fell into place for Arsenal in the cup competition last year, it was like it was written in the stars.
"This goalkeeper comes in – been at the club for 10 years and not played 10 games – and he stops everything! He was a man possessed, he was absolutely incredible.
"For me he was the number one... but Arteta’s the man and he’s chosen a different goalkeeper."