He said: "They are not top of the table for nothing. The way they have played this season is unbelievable and I still think they will win the league.
"They had a lot of players missing yesterday and when they are back they will win the title. I just think it's the way Arsenal get their results. I have been watching their games and they are the best team."
Arsenal were way below par on their second visit to the North-East in four days and Middlesbrough capitalised with a high-intensity performance that was as fluent as it was energetic to lift them out of the bottom three and ease the pressure on manager Gareth Southgate.
"They were not worse than I thought," said Aliadiere of his former employers. "We made them have a game. We decided to press them from the start to the end and a team like Arsenal does not like that. If you don't let them play it is difficult for any team.
"I've been waiting for this game all season. It's my old team, first time I've played against Arsenal and I was very much motivated to win.
"They did not miss just [Cesc] Fabregas but [Alexander] Hleb as well, who has been doing an unbelievable job. Those two players create a lot of chances and a lot of things for Arsenal which they missed yesterday."