Rooney was on punditry duty for the Gunners' away clash in Champions League action against Inter Milan on Tuesday evening, in which Arsenal claimed a 3-1 victory thanks to goals from Gabriel Jesus and Viktor Gyokeres.
Arsenal, who are top of the Champions League and Premier League whilst also being in the FA Cup and EFL Cup, are having an incredible season to say the least.
Manager Mikel Arteta has led his side to new heights and will be aiming to land a piece of silverware before the season is over. However, despite their fine form, Rooney believes his old side could run rings around them.
Speaking on Amazon Prime, Arsenal legend Theo Walcott asked:
"It's kind of flipped hasn't it? Would your '08 team compete - well you would compete with this team (Arsenal) - but how does it compare to your 2008 team which was probably the best team I have ever played against?
"This squad, compared to that one."
Rooney gave a blunt response: "Yeah, we'd batter them. I think we would, I have to be honest."
During that 2008/2009 campaign, Rooney featured 39 times across all competitions for United, netting an impressive 18 goals throughout the season.
Arsenal, who sit seven points clear of Manchester City and Aston Villa in the league face United this weekend and Rooney will likely be on pundit duty once more to compare the current side against the Gunners.