You're contradicting yourself there. Best defence, yet need two fullbacks?
Also, just by adding two "big" names, does not success guarantee.
Their squad is distinctly average and needs a sizeable overhaul; Rojo, Jones, Smalling, Shaw, Carrick, Mikhitahryan, Mata, Ibrahimovic, Lingard, should all be replaced with a better version. Possibly even a goalkeeper if De Gea gets cheesed off.
But they won't; they will continue to buy a "big" name for crazy money, because it keeps them in the limelight, sells shirts to the apostles and appeases the creditors.
Which then leads to ignoramus' (ignorami?) on social media telling us "manyoo are back", leading to more coverage, more shirts and pencil cases sold across Asia. And so, the financial wheel continues to rotate.
I'm not a businessman whatsoever, but even I can see that their model is atrocious and solely relies on past successes and keeping them in the spotlight, no matter how.